GeoAlchemy 2 Documentation

Using SQLAlchemy with Spatial Databases.

GeoAlchemy 2 provides extensions to SQLAlchemy for working with spatial databases.

GeoAlchemy 2 focuses on PostGIS. PostGIS 1.5 and PostGIS 2 are supported.

SpatiaLite is also supported, but using GeoAlchemy 2 with SpatiaLite requires some specific configuration on the application side. GeoAlchemy 2 works with SpatiaLite 4.3.0 and higher.

GeoAlchemy 2 aims to be simpler than its predecessor, GeoAlchemy. Simpler to use, and simpler to maintain.

The current version of this documentation applies to the version 0.9.0 of GeoAlchemy 2.

Requirements

GeoAlchemy 2 requires SQLAlchemy 0.8. GeoAlchemy 2 does not work with SQLAlchemy 0.7 and lower.

Installation

GeoAlchemy 2 is available on the Python Package Index. So it can be installed with the standard pip or easy_install tools.

What’s New in GeoAlchemy 2

  • GeoAlchemy 2 supports PostGIS’ geometry type, as well as the geography and raster types.
  • The first series had its own namespace for spatial functions. With GeoAlchemy 2, spatial functions are called like any other SQLAlchemy function, using func, which is SQLAlchemy’s standard way of calling SQL functions.
  • GeoAlchemy 2 works with SQLAlchemy’s ORM, as well as with SQLAlchemy’s SQL Expression Language (a.k.a the SQLAlchemy Core). (This is thanks to SQLAlchemy’s new type-level comparator system.)
  • GeoAlchemy 2 supports reflection of geometry and geography columns.
  • GeoAlchemy 2 adds to_shape, from_shape functions for a better integration with Shapely.

Migrate to GeoAlchemy 2

This section describes how to migrate an application from the first series of GeoAlchemy to GeoAlchemy 2.

Defining Geometry Columns

The first series has specific types like Point, LineString and Polygon. These are gone, the geoalchemy2.types.Geometry type should be used instead, and a geometry_type can be passed to it.

So, for example, a polygon column that used to be defined like this:

geom = Column(Polygon)

is now defined like this:

geom = Column(Geometry('POLYGON'))

This change is related to GeoAlchemy 2 supporting the geoalchemy2.types.Geography type.

Calling Spatial Functions

The first series has its own namespace/object for calling spatial functions, namely geoalchemy.functions. With GeoAlchemy 2, SQLAlchemy’s func object should be used.

For example, the expression

functions.buffer(functions.centroid(box), 10, 2)

would be rewritten to this with GeoAlchemy 2:

func.ST_Buffer(func.ST_Centroid(box), 10, 2)

Also, as the previous example hinted it, the names of spatial functions are now all prefixed with ST_. (This is to be consistent with PostGIS and the SQL-MM standard.) The ST_ prefix should be used even when applying spatial functions to columns, geoalchemy2.elements.WKTElement, or geoalchemy2.elements.WKTElement objects:

Lake.geom.ST_Buffer(10, 2)
lake_table.c.geom.ST_Buffer(10, 2)
lake.geom.ST_Buffer(10, 2)

WKB and WKT Elements

The first series has classes like PersistentSpatialElement, PGPersistentSpatialElement, WKTSpatialElement.

They’re all gone, and replaced by two classes only: geoalchemy2.elements.WKTElement and geoalchemy2.elements.WKBElement.

geoalchemy2.elements.WKTElement is to be used in expressions where a geometry with a specific SRID should be specified. For example:

Lake.geom.ST_Touches(WKTElement('POINT(1 1)', srid=4326))

If no SRID need be specified, a string can used directly:

Lake.geom.ST_Touches('POINT(1 1)')

See the Migrate to GeoAlchemy 2 page for details on how to migrate a GeoAlchemy application to GeoAlchemy 2.

Tutorials

GeoAlchemy 2 works with both SQLAlchemy’s Object Relational Mapping (ORM) and SQL Expression Language. This documentation provides a tutorial for each system. If you’re new to GeoAlchemy 2 start with this.

ORM Tutorial

(This tutorial is greatly inspired by the SQLAlchemy ORM Tutorial, which is recommended reading, eventually.)

GeoAlchemy does not provide an Object Relational Mapper (ORM), but works well with the SQLAlchemy ORM. This tutorial shows how to use the SQLAlchemy ORM with spatial tables, using GeoAlchemy.

Connect to the DB

For this tutorial we will use a PostGIS 2 database. To connect we use SQLAlchemy’s create_engine() function:

>>> from sqlalchemy import create_engine
>>> engine = create_engine('postgresql://gis:gis@localhost/gis', echo=True)

In this example the name of the database, the database user, and the database password, is gis.

The echo flag is a shortcut to setting up SQLAlchemy logging, which is accomplished via Python’s standard logging module. With it is enabled, we’ll see all the generated SQL produced.

The return value of create_engine is an Engine object, which represents the core interface to the database.

Declare a Mapping

When using the ORM, the configurational process starts by describing the database tables we’ll be dealing with, and then by defining our own classes which will be mapped to those tables. In modern SQLAlchemy, these two tasks are usually performed together, using a system known as Declarative, which allows us to create classes that include directives to describe the actual database table they will be mapped to.

>>> from sqlalchemy.ext.declarative import declarative_base
>>> from sqlalchemy import Column, Integer, String
>>> from geoalchemy2 import Geometry
>>>
>>> Base = declarative_base()
>>>
>>> class Lake(Base):
...     __tablename__ = 'lake'
...     id = Column(Integer, primary_key=True)
...     name = Column(String)
...     geom = Column(Geometry('POLYGON'))

The Lake class establishes details about the table being mapped, including the name of the table denoted by __tablename__, and three columns id, name, and geom. The id column will be the primary key of the table. The geom column is a geoalchemy2.types.Geometry column whose geometry_type is POLYGON.

Create the Table in the Database

The Lake class has a corresponding Table object representing the database table. This Table object was created automatically by SQLAlchemy, it is referenced to by the Lake.__table__ property:

>>> Lake.__table__
Table('lake', MetaData(bind=None), Column('id', Integer(), table=<lake>,
primary_key=True, nullable=False), Column('name', String(), table=<lake>),
Column('geom', Polygon(srid=4326), table=<lake>), schema=None)

To create the lake table in the database:

>>> Lake.__table__.create(engine)

If we wanted to drop the table we’d use:

>>> Lake.__table__.drop(engine)

Create an Instance of the Mapped Class

With the mapping declared, we can create a Lake object:

>>> lake = Lake(name='Majeur', geom='POLYGON((0 0,1 0,1 1,0 1,0 0))')
>>> lake.geom
'POLYGON((0 0,1 0,1 1,0 1,0 0))'
>>> str(lake.id)
'None'

A WKT is passed to the Lake constructor for its geometry. This WKT represents the shape of our lake. Since we have not yet told SQLAlchemy to persist the lake object, its id is None.

The EWKT (Extended WKT) format is also supported. So, for example, if the spatial reference system for the geometry column were 4326, the string SRID=4326;POLYGON((0 0,1 0,1,0 1,0 0)) could be used as the geometry representation.

Create a Session

The ORM interacts with the database through a Session. Let’s create a Session class:

>>> from sqlalchemy.orm import sessionmaker
>>> Session = sessionmaker(bind=engine)

This custom-made Session class will create new Session objects which are bound to our database. Then, whenever we need to have a conversation with the database, we instantiate a Session:

>>> session = Session()

The above Session is associated with our PostgreSQL Engine, but it hasn’t opened any connection yet.

Add New Objects

To persist our Lake object, we add() it to the Session:

>>> session.add(lake)

At this point the lake object has been added to the Session, but no SQL has been issued to the database. The object is in a pending state. To persist the object a flush or commit operation must occur (commit implies flush):

>>> session.commit()

We can now query the database for Majeur:

>>> our_lake = session.query(Lake).filter_by(name='Majeur').first()
>>> our_lake.name
u'Majeur'
>>> our_lake.geom
<WKBElement at 0x9af594c; '0103000000010000000500000000000000000000000000000000000000000000000000f03f0000000000000000000000000000f03f000000000000f03f0000000000000000000000000000f03f00000000000000000000000000000000'>
>>> our_lake.id
1

our_lake.geom is a geoalchemy2.elements.WKBElement, which a type provided by GeoAlchemy. geoalchemy2.elements.WKBElement wraps a WKB value returned by the database.

Let’s add more lakes:

>>> session.add_all([
...     Lake(name='Garde', geom='POLYGON((1 0,3 0,3 2,1 2,1 0))'),
...     Lake(name='Orta', geom='POLYGON((3 0,6 0,6 3,3 3,3 0))')
... ])
>>> session.commit()

Query

A Query object is created using the query() function on Session. For example here’s a Query that loads Lake instances ordered by their names:

>>> query = session.query(Lake).order_by(Lake.name)

Any Query is iterable:

>>> for lake in query:
...     print lake.name
...
Garde
Majeur
Orta

Another way to execute the query and get a list of Lake objects involves calling all() on the Query:

>>> lakes = session.query(Lake).order_by(Lake.name).all()

The SQLAlchemy ORM Tutorial’s Querying section provides more examples of queries.

Make Spatial Queries

Using spatial filters in SQL SELECT queries is very common. Such queries are performed by using spatial relationship functions, or operators, in the WHERE clause of the SQL query.

For example, to find the Lake s that contain the point POINT(4 1), we can use this Query:

>>> from sqlalchemy import func
>>> query = session.query(Lake).filter(
...             func.ST_Contains(Lake.geom, 'POINT(4 1)'))
...
>>> for lake in query:
...     print lake.name
...
Orta

GeoAlchemy allows rewriting this Query more concisely:

>>> query = session.query(Lake).filter(Lake.geom.ST_Contains('POINT(4 1)'))
>>> for lake in query:
...     print lake.name
...
Orta

Here the ST_Contains function is applied to the Lake.geom column property. In that case the column property is actually passed to the function, as its first argument.

Here’s another spatial filtering query, based on ST_Intersects:

>>> query = session.query(Lake).filter(
...             Lake.geom.ST_Intersects('LINESTRING(2 1,4 1)'))
...
>>> for lake in query:
...     print lake.name
...
Garde
Orta

We can also apply relationship functions to geoalchemy2.elements.WKBElement. For example:

>>> lake = session.query(Lake).filter_by(name='Garde').one()
>>> print session.scalar(lake.geom.ST_Intersects('LINESTRING(2 1,4 1)'))
True

session.scalar allows executing a clause and returning a scalar value (a boolean value in this case).

The GeoAlchemy functions all start with ST_. Operators are also called as functions, but the function names don’t include the ST_ prefix. As an example let’s use PostGIS’ && operator, which allows testing whether the bounding boxes of geometries intersect. GeoAlchemy provides the intersects function for that:

>>> query = session.query
>>> query = session.query(Lake).filter(
...             Lake.geom.intersects('LINESTRING(2 1,4 1)'))
...
>>> for lake in query:
...     print lake.name
...
Garde
Orta

Set Spatial Relationships in the Model

Let’s assume that in addition to lake we have another table, treasure, that includes treasure locations. And let’s say that we are interested in discovering the treasures hidden at the bottom of lakes.

The Treasure class is the following:

>>> class Treasure(Base):
...      __tablename__ = 'treasure'
...      id = Column(Integer, primary_key=True)
...      geom = Column(Geometry('POINT'))

We can now add a relationship to the Lake table to automatically load the treasures contained by each lake:

>>> from sqlalchemy.orm import relationship, backref
>>> class Lake(Base):
...     __tablename__ = 'lake'
...     id = Column(Integer, primary_key=True)
...     name = Column(String)
...     geom = Column(Geometry('POLYGON'))
...     treasures = relationship(
...         'Treasure',
...         primaryjoin='func.ST_Contains(foreign(Lake.geom), Treasure.geom).as_comparison(1, 2)',
...         backref=backref('lake', uselist=False),
...         viewonly=True,
...         uselist=True,
...     )

Note the use of the as_comparison function. It is required for using an SQL function (ST_Contains here) in a primaryjoin condition. This only works with SQLAlchemy 1.3, as the as_comparison function did not exist before that version. See the Custom operators based on SQL function section of the SQLAlchemy documentation for more information.

Some information on the parameters used for configuring this relationship:

  • backref is used to provide the name of property to be placed on the class that handles this relationship in the other direction, namely Treasure;
  • viewonly=True specifies that the relationship is used only for loading objects, and not for persistence operations;
  • uselist=True indicates that the property should be loaded as a list, as opposed to a scalar.

Also, note that the treasures property on lake objects (and the lake property on treasure objects) is loaded “lazily” when the property is first accessed. Another loading strategy may be configured in the relationship. For example you’d use lazy='joined' for related items to be loaded “eagerly” in the same query as that of the parent, using a JOIN or LEFT OUTER JOIN.

See the Relationships API section of the SQLAlchemy documentation for more detail on the relationship function, and all the parameters that can be used to configure it.

Use Other Spatial Functions

Here’s a Query that calculates the areas of buffers for our lakes:

>>> from sqlalchemy import func
>>> query = session.query(Lake.name,
...                       func.ST_Area(func.ST_Buffer(Lake.geom, 2)) \
...                           .label('bufferarea'))
>>> for row in query:
...     print '%s: %f' % (row.name, row.bufferarea)
...
Majeur: 21.485781
Garde: 32.485781
Orta: 45.485781

This Query applies the PostGIS ST_Buffer function to the geometry column of every row of the lake table. The return value is a list of rows, where each row is actually a tuple of two values: the lake name, and the area of a buffer of the lake. Each tuple is actually an SQLAlchemy KeyedTuple object, which provides property type accessors.

Again, the Query can written more concisely:

>>> query = session.query(Lake.name,
...                       Lake.geom.ST_Buffer(2).ST_Area().label('bufferarea'))
>>> for row in query:
...     print '%s: %f' % (row.name, row.bufferarea)
...
Majeur: 21.485781
Garde: 32.485781
Orta: 45.485781

Obviously, processing and measurement functions can also be used in WHERE clauses. For example:

>>> lake = session.query(Lake).filter(
...             Lake.geom.ST_Buffer(2).ST_Area() > 33).one()
...
>>> print lake.name
Orta

And, like any other functions supported by GeoAlchemy, processing and measurement functions can be applied to geoalchemy2.elements.WKBElement. For example:

>>> lake = session.query(Lake).filter_by(name='Majeur').one()
>>> bufferarea = session.scalar(lake.geom.ST_Buffer(2).ST_Area())
>>> print '%s: %f' % (lake.name, bufferarea)
Majeur: 21.485781
Majeur: 21.485781

Use Raster functions

A few functions (like ST_Transform(), ST_Union(), ST_SnapToGrid(), …) can be used on both geoalchemy2.types.Geometry and geoalchemy2.types.Raster types. In GeoAlchemy2, these functions are only defined for Geometry as it can not be defined for several types at the same time. Thus using these functions on Raster requires minor tweaking to enforce the type by passing the type_=Raster argument to the function:

>>> query = session.query(Lake.raster.ST_Transform(2154, type_=Raster))

Further Reference

Core Tutorial

(This tutorial is greatly inspired from the SQLAlchemy SQL Expression Language Tutorial, which is recommended reading, eventually.)

This tutorial shows how to use the SQLAlchemy Expression Language (a.k.a. SQLAlchemy Core) with GeoAlchemy. As defined by the SQLAlchemy documentation itself, in contrast to the ORM’s domain-centric mode of usage, the SQL Expression Language provides a schema-centric usage paradigm.

Connect to the DB

For this tutorial we will use a PostGIS 2 database. To connect we use SQLAlchemy’s create_engine() function:

>>> from sqlalchemy import create_engine
>>> engine = create_engine('postgresql://gis:gis@localhost/gis', echo=True)

In this example the name of the database, the database user, and the database password, is gis.

The echo flag is a shortcut to setting up SQLAlchemy logging, which is accomplished via Python’s standard logging module. With it is enabled, we’ll see all the generated SQL produced.

The return value of create_engine is an Engine object, which respresents the core interface to the database.

Define a Table

The very first object that we need to create is a Table. Here we create a lake_table object, which will correspond to the lake table in the database:

>>> from sqlalchemy import Table, Column, Integer, String, MetaData
>>> from geoalchemy2 import Geometry
>>>
>>> metadata = MetaData()
>>> lake_table = Table('lake', metadata,
...     Column('id', Integer, primary_key=True),
...     Column('name', String),
...     Column('geom', Geometry('POLYGON'))
... )

This table is composed of three columns, id, name and geom. The geom column is a geoalchemy2.types.Geometry column whose geometry_type is POLYGON.

Any Table object is added to a MetaData object, which is a catalog of Table objects (and other related objects).

Create the Table

With our Table being defined we’re ready (to have SQLAlchemy) create it in the database:

>>> lake_table.create(engine)

Calling create_all() on metadata would have worked equally well:

>>> metadata.create_all(engine)

In that case every Table that’s referenced to by metadata would be created in the database. The metadata object includes one Table here, our now well-known lake_table object.

Reflecting tables

The reflection system of SQLAlchemy can be used on tables containing geoalchemy2.types.Geometry or geoalchemy2.types.Geography columns. In this case, the type must be imported to be registered into SQLAlchemy, even if it is not used explicitely.

>>> from geoalchemy2 import Geometry  # <= not used but must be imported
>>> from sqlalchemy import create_engine, MetaData
>>> engine = create_engine("postgresql://myuser:mypass@mydb.host.tld/mydbname")
>>> meta = MetaData()
>>> meta.reflect(bind=engine)

Insertions

We want to insert records into the lake table. For that we need to create an Insert object. SQLAlchemy provides multiple constructs for creating an Insert object, here’s one:

>>> ins = lake_table.insert()
>>> str(ins)
INSERT INTO lake (id, name, geom) VALUES (:id, :name, ST_GeomFromEWKT(:geom))

The geom column being a Geometry column, the :geom bind value is wrapped in a ST_GeomFromEWKT call.

To limit the columns named in the INSERT query the values() method can be used:

>>> ins = lake_table.insert().values(name='Majeur',
...                                  geom='POLYGON((0 0,1 0,1 1,0 1,0 0))')
...
>>> str(ins)
INSERT INTO lake (name, geom) VALUES (:name, ST_GeomFromEWKT(:geom))

Tip

The string representation of the SQL expression does not include the data placed in values. We got named bind parameters instead. To view the data we can get a compiled form of the expression, and ask for its params:

>>> ins.compile.params()
{'geom': 'POLYGON((0 0,1 0,1 1,0 1,0 0))', 'name': 'Majeur'}

Up to now we’ve created an INSERT query but we haven’t sent this query to the database yet. Before being able to send it to the database we need a database Connection. We can get a Connection from the Engine object we created earlier:

>>> conn = engine.connect()

We’re now ready to execute our INSERT statement:

>>> result = conn.execute(ins)

This is what the logging system should output:

INSERT INTO lake (name, geom) VALUES (%(name)s, ST_GeomFromEWKT(%(geom)s)) RETURNING lake.id
{'geom': 'POLYGON((0 0,1 0,1 1,0 1,0 0))', 'name': 'Majeur'}
COMMIT

The value returned by conn.execute(), stored in result, is a sqlalchemy.engine.ResultProxy object. In the case of an INSERT we can get the primary key value which was generated from our statement:

>>> result.inserted_primary_key
[1]

Instead of using values() to specify our INSERT data, we can send the data to the execute() method on Connection. So we could rewrite things as follows:

>>> conn.execute(lake_table.insert(),
...              name='Majeur', geom='POLYGON((0 0,1 0,1 1,0 1,0 0))')

Now let’s use another form, allowing to insert multiple rows at once:

>>> conn.execute(lake_table.insert(), [
...     {'name': 'Garde', 'geom': 'POLYGON((1 0,3 0,3 2,1 2,1 0))'},
...     {'name': 'Orta', 'geom': 'POLYGON((3 0,6 0,6 3,3 3,3 0))'}
...     ])
...

Tip

In the above examples the geometries are specified as WKT strings. Specifying them as EWKT strings is also supported.

Selections

Inserting involved creating an Insert object, so it’d come to no surprise that Selecting involves creating a Select object. The primary construct to generate SELECT statements is SQLAlchemy`s select() function:

>>> from sqlalchemy.sql import select
>>> s = select([lake_table])
>>> str(s)
SELECT lake.id, lake.name, ST_AsEWKB(lake.geom) AS geom FROM lake

The geom column being a Geometry it is wrapped in a ST_AsEWKB call when specified as a column in a SELECT statement.

We can now execute the statement and look at the results:

>>> result = conn.execute(s)
>>> for row in result:
...     print 'name:', row['name'], '; geom:', row['geom'].desc
...
name: Majeur ; geom: 0103...
name: Garde ; geom: 0103...
name: Orta ; geom: 0103...

row['geom'] is a geoalchemy2.types.WKBElement instance. In this example we just get an hexadecimal representation of the geometry’s WKB value using the desc property.

Spatial Query

As spatial database users executing spatial queries is of a great interest to us. There comes GeoAlchemy!

Spatial relationship

Using spatial filters in SQL SELECT queries is very common. Such queries are performed by using spatial relationship functions, or operators, in the WHERE clause of the SQL query.

For example, to find lakes that contain the point POINT(4 1), we can use this:

>>> from sqlalchemy import func
>>> s = select([lake_table],
               func.ST_Contains(lake_table.c.geom, 'POINT(4 1)'))
>>> str(s)
SELECT lake.id, lake.name, ST_AsEWKB(lake.geom) AS geom FROM lake WHERE ST_Contains(lake.geom, :param_1)
>>> result = conn.execute(s)
>>> for row in result:
...     print 'name:', row['name'], '; geom:', row['geom'].desc
...
name: Orta ; geom: 0103...

GeoAlchemy allows rewriting this more concisely:

>>> s = select([lake_table], lake_table.c.geom.ST_Contains('POINT(4 1)'))
>>> str(s)
SELECT lake.id, lake.name, ST_AsEWKB(lake.geom) AS geom FROM lake WHERE ST_Contains(lake.geom, :param_1)

Here the ST_Contains function is applied to lake.c.geom. And the generated SQL the lake.geom column is actually passed to the ST_Contains function as the first argument.

Here’s another spatial query, based on ST_Intersects:

   >>> s = select([lake_table],
   ...            lake_table.c.geom.ST_Intersects('LINESTRING(2 1,4 1)'))
   >>> result = conn.execute(s)
   >>> for row in result:
   ...     print 'name:', row['name'], '; geom:', row['geom'].desc
   ...
   name: Garde ; geom: 0103...
   name: Orta ; geom: 0103...

This query selects lakes whose geometries intersect ``LINESTRING(2 1,4 1)``.

The GeoAlchemy functions all start with ST_. Operators are also called as functions, but the names of operator functions don’t include the ST_ prefix.

As an example let’s use PostGIS’ && operator, which allows testing whether the bounding boxes of geometries intersect. GeoAlchemy provides the intersects function for that:

>>> s = select([lake_table],
...            lake_table.c.geom.intersects('LINESTRING(2 1,4 1)'))
>>> result = conn.execute(s)
>>> for row in result:
...     print 'name:', row['name'], '; geom:', row['geom'].desc
...
name: Garde ; geom: 0103...
name: Orta ; geom: 0103...
Processing and Measurement

Here’s a Select that calculates the areas of buffers for our lakes:

>>> s = select([lake_table.c.name,
                func.ST_Area(
                    lake_table.c.geom.ST_Buffer(2)).label('bufferarea')])
>>> str(s)
SELECT lake.name, ST_Area(ST_Buffer(lake.geom, %(param_1)s)) AS bufferarea FROM lake
>>> result = conn.execute(s)
>>> for row in result:
...     print '%s: %f' % (row['name'], row['bufferarea'])
Majeur: 21.485781
Garde: 32.485781
Orta: 45.485781

Obviously, processing and measurement functions can also be used in WHERE clauses. For example:

>>> s = select([lake_table.c.name],
               lake_table.c.geom.ST_Buffer(2).ST_Area() > 33)
>>> str(s)
SELECT lake.name FROM lake WHERE ST_Area(ST_Buffer(lake.geom, :param_1)) > :ST_Area_1
>>> result = conn.execute(s)
>>> for row in result:
...     print row['name']
Orta

And, like any other functions supported by GeoAlchemy, processing and measurement functions can be applied to geoalchemy2.elements.WKBElement. For example:

>>> s = select([lake_table], lake_table.c.name == 'Majeur')
>>> result = conn.execute(s)
>>> lake = result.fetchone()
>>> bufferarea = conn.scalar(lake[lake_table.c.geom].ST_Buffer(2).ST_Area())
>>> print '%s: %f' % (lake['name'], bufferarea)
Majeur: 21.485781

Use Raster functions

A few functions (like ST_Transform(), ST_Union(), ST_SnapToGrid(), …) can be used on both geoalchemy2.types.Geometry and geoalchemy2.types.Raster types. In GeoAlchemy2, these functions are only defined for Geometry as it can not be defined for several types at the same time. Thus using these functions on Raster requires minor tweaking to enforce the type by passing the type_=Raster argument to the function:

>>> s = select([func.ST_Transform(
                    lake_table.c.raster,
                    2154,
                    type_=Raster)
                .label('transformed_raster')])

Further Reference

SpatiaLite Tutorial

GeoAlchemy 2’s main target is PostGIS. But GeoAlchemy 2 also supports SpatiaLite, the spatial extension to SQLite. This tutorial describes how to use GeoAlchemy 2 with SpatiaLite. It’s based on the ORM Tutorial, which you may want to read first.

Connect to the DB

Just like when using PostGIS connecting to a SpatiaLite database requires an Engine. This is how you create one for SpatiaLite:

>>> from sqlalchemy import create_engine
>>> from sqlalchemy.event import listen
>>>
>>> def load_spatialite(dbapi_conn, connection_record):
...     dbapi_conn.enable_load_extension(True)
...     dbapi_conn.load_extension('/usr/lib/x86_64-linux-gnu/mod_spatialite.so')
...
>>>
>>> engine = create_engine('sqlite:///gis.db', echo=True)
>>> listen(engine, 'connect', load_spatialite)

The call to create_engine creates an engine bound to the database file gis.db. After that a connect listener is registered on the engine. The listener is responsible for loading the SpatiaLite extension, which is a necessary operation for using SpatiaLite through SQL.

At this point you can test that you are able to connect to the database:

>> conn = engine.connect()
2018-05-30 17:12:02,675 INFO sqlalchemy.engine.base.Engine SELECT CAST('test plain returns' AS VARCHAR(60)) AS anon_1
2018-05-30 17:12:02,676 INFO sqlalchemy.engine.base.Engine ()
2018-05-30 17:12:02,676 INFO sqlalchemy.engine.base.Engine SELECT CAST('test unicode returns' AS VARCHAR(60)) AS anon_1
2018-05-30 17:12:02,676 INFO sqlalchemy.engine.base.Engine ()

You can also check that the gis.db SQLite database file was created on the file system.

One additional step is required for using SpatiaLite: create the geometry_columns and spatial_ref_sys metadata tables. This is done by calling SpatiaLite’s InitSpatialMetaData function:

>>> from sqlalchemy.sql import select, func
>>>
>>> conn.execute(select([func.InitSpatialMetaData()]))

Note that this operation may take some time the first time it is executed for a database. When InitSpatialMetaData is executed again it will report an error:

InitSpatiaMetaData() error:"table spatial_ref_sys already exists"

You can safely ignore that error.

Before going further we can close the current connection:

>>> conn.close()

Declare a Mapping

Now that we have a working connection we can go ahead and create a mapping between a Python class and a database table.

>>> from sqlalchemy.ext.declarative import declarative_base
>>> from sqlalchemy import Column, Integer, String
>>> from geoalchemy2 import Geometry
>>>
>>> Base = declarative_base()
>>>
>>> class Lake(Base):
...     __tablename__ = 'lake'
...     id = Column(Integer, primary_key=True)
...     name = Column(String)
...     geom = Column(Geometry(geometry_type='POLYGON', management=True))

This basically works in the way as with PostGIS. The difference is the management argument that must be set to True.

Setting management to True indicates that the AddGeometryColumn and DiscardGeometryColumn management functions will be used for the creation and removal of the geometry column. This is required with SpatiaLite.

Create the Table in the Database

We can now create the lake table in the gis.db database:

>>> Lake.__table__.create(engine)

If we wanted to drop the table we’d use:

>>> Lake.__table__.drop(engine)

There’s nothing specific to SpatiaLite here.

Create a Session

When using the SQLAlchemy ORM the ORM interacts with the database through a Session.

>>> from sqlalchemy.orm import sessionmaker
>>> Session = sessionmaker(bind=engine)
>>> session = Session()

The session is associated with our SpatiaLite Engine. Again, there’s nothing specific to SpatiaLite here.

Add New Objects

We can now create and insert new Lake objects into the database, the same way we’d do it using GeoAlchemy 2 with PostGIS.

>>> lake = Lake(name='Majeur', geom='POLYGON((0 0,1 0,1 1,0 1,0 0))')
>>> session.add(lake)
>>> session.commit()

We can now query the database for Majeur:

>>> our_lake = session.query(Lake).filter_by(name='Majeur').first()
>>> our_lake.name
u'Majeur'
>>> our_lake.geom
<WKBElement at 0x9af594c; '0103000000010000000500000000000000000000000000000000000000000000000000f03f0000000000000000000000000000f03f000000000000f03f0000000000000000000000000000f03f00000000000000000000000000000000'>
>>> our_lake.id
1

Let’s add more lakes:

>>> session.add_all([
...     Lake(name='Garde', geom='POLYGON((1 0,3 0,3 2,1 2,1 0))'),
...     Lake(name='Orta', geom='POLYGON((3 0,6 0,6 3,3 3,3 0))')
... ])
>>> session.commit()

Query

Let’s make a simple, non-spatial, query:

>>> query = session.query(Lake).order_by(Lake.name)
>>> for lake in query:
...     print(lake.name)
...
Garde
Majeur
Orta

Now a spatial query:

>>> from geolachemy2 import WKTElement
>>> query = session.query(Lake).filter(
...             func.ST_Contains(Lake.geom, WKTElement('POINT(4 1)')))
...
>>> for lake in query:
...     print(lake.name)
...
Orta

Here’s another spatial query, using ST_Intersects this time:

>>> query = session.query(Lake).filter(
...             Lake.geom.ST_Intersects(WKTElement('LINESTRING(2 1,4 1)')))
...
>>> for lake in query:
...     print(lake.name)
...
Garde
Orta

We can also apply relationship functions to geoalchemy2.elements.WKBElement. For example:

>>> lake = session.query(Lake).filter_by(name='Garde').one()
>>> print(session.scalar(lake.geom.ST_Intersects(WKTElement('LINESTRING(2 1,4 1)'))))
1

session.scalar allows executing a clause and returning a scalar value (an integer value in this case).

The value 1 indicates that the lake “Garde” does intersects the LINESTRING(2 1,4 1) geometry. See the SpatiaLite SQL functions reference list for more information.

Further Reference

Reference Documentation

Types

This module defines the geoalchemy2.types.Geometry, geoalchemy2.types.Geography, and geoalchemy2.types.Raster classes, that are used when defining geometry, geography and raster columns/properties in models.

Reference

class geoalchemy2.types.CompositeType[source]

Bases: sqlalchemy.sql.type_api.UserDefinedType

A wrapper for geoalchemy2.elements.CompositeElement, that can be used as the return type in PostgreSQL functions that return composite values.

This is used as the base class of geoalchemy2.types.GeometryDump.

class comparator_factory(expr)[source]

Bases: sqlalchemy.sql.type_api.Comparator

typemap = {}

Dictionary used for defining the content types and their corresponding keys. Set in subclasses.

class geoalchemy2.types.Geography(geometry_type='GEOMETRY', srid=-1, dimension=2, spatial_index=True, use_N_D_index=False, management=False, use_typmod=None, from_text=None, name=None)[source]

Bases: geoalchemy2.types._GISType

The Geography type.

Creating a geography column is done like this:

Column(Geography(geometry_type='POINT', srid=4326))

See geoalchemy2.types._GISType for the list of arguments that can be passed to the constructor.

ElementType

alias of geoalchemy2.elements.WKBElement

as_binary = 'ST_AsBinary'

The “as binary” function to use. Used by the parent class’ column_expression method.

from_text = 'ST_GeogFromText'

The FromText geography constructor. Used by the parent class’ bind_expression method.

name = 'geography'

Type name used for defining geography columns in CREATE TABLE.

class geoalchemy2.types.Geometry(geometry_type='GEOMETRY', srid=-1, dimension=2, spatial_index=True, use_N_D_index=False, management=False, use_typmod=None, from_text=None, name=None)[source]

Bases: geoalchemy2.types._GISType

The Geometry type.

Creating a geometry column is done like this:

Column(Geometry(geometry_type='POINT', srid=4326))

See geoalchemy2.types._GISType for the list of arguments that can be passed to the constructor.

If srid is set then the WKBElement objects resulting from queries will have that SRID, and, when constructing the WKBElement objects, the SRID won’t be read from the data returned by the database. If srid is not set (meaning it’s -1) then the SRID set in WKBElement objects will be read from the data returned by the database.

ElementType

alias of geoalchemy2.elements.WKBElement

as_binary = 'ST_AsEWKB'

The “as binary” function to use. Used by the parent class’ column_expression method.

from_text = 'ST_GeomFromEWKT'

The “from text” geometry constructor. Used by the parent class’ bind_expression method.

name = 'geometry'

Type name used for defining geometry columns in CREATE TABLE.

class geoalchemy2.types.GeometryDump[source]

Bases: geoalchemy2.types.CompositeType

The return type for functions like ST_Dump, consisting of a path and a geom field. You should normally never use this class directly.

typemap = {'geom': <class 'geoalchemy2.types.Geometry'>, 'path': ARRAY(Integer())}

Dictionary defining the contents of a geometry_dump.

class geoalchemy2.types.Raster(*args, **kwargs)[source]

Bases: geoalchemy2.types._GISType

The Raster column type.

Creating a raster column is done like this:

Column(Raster)

This class defines the result_processor method, so that raster values received from the database are converted to geoalchemy2.elements.RasterElement objects.

Constructor arguments:

spatial_index

Indicate if a spatial index should be created. Default is True.
ElementType

alias of geoalchemy2.elements.RasterElement

as_binary = 'raster'

The “as binary” function to use. Used by the parent class’ column_expression method.

comparator_factory

alias of geoalchemy2.comparator.BaseComparator

from_text = 'raster'

The “from text” raster constructor. Used by the parent class’ bind_expression method.

name = 'raster'

Type name used for defining raster columns in CREATE TABLE.

class geoalchemy2.types._GISType(geometry_type='GEOMETRY', srid=-1, dimension=2, spatial_index=True, use_N_D_index=False, management=False, use_typmod=None, from_text=None, name=None)[source]

Bases: sqlalchemy.sql.type_api.UserDefinedType

The base class for geoalchemy2.types.Geometry and geoalchemy2.types.Geography.

This class defines bind_expression and column_expression methods that wrap column expressions in ST_GeomFromEWKT, ST_GeogFromText, or ST_AsEWKB calls.

This class also defines result_processor and bind_processor methods. The function returned by result_processor converts WKB values received from the database to geoalchemy2.elements.WKBElement objects. The function returned by bind_processor converts geoalchemy2.elements.WKTElement objects to EWKT strings.

Constructor arguments:

geometry_type

The geometry type.

Possible values are:

  • "GEOMETRY",
  • "POINT",
  • "LINESTRING",
  • "POLYGON",
  • "MULTIPOINT",
  • "MULTILINESTRING",
  • "MULTIPOLYGON",
  • "GEOMETRYCOLLECTION",
  • "CURVE",
  • None.

The latter is actually not supported with geoalchemy2.types.Geography.

When set to None then no “geometry type” constraints will be attached to the geometry type declaration. Using None here is not compatible with setting management to True.

Default is "GEOMETRY".

srid

The SRID for this column. E.g. 4326. Default is -1.

dimension

The dimension of the geometry. Default is 2.

With management set to True, that is when AddGeometryColumn is used to add the geometry column, there are two constraints:

  • The geometry_type must not end with "ZM". This is due to PostGIS’ AddGeometryColumn failing with ZM geometry types. Instead the “simple” geometry type (e.g. POINT rather POINTZM) should be used with dimension set to 4.
  • When the geometry_type ends with "Z" or "M" then dimension must be set to 3.

With management set to False (the default) dimension is not taken into account, and the actual dimension is fully defined with the geometry_type.

spatial_index

Indicate if a spatial index should be created. Default is True.
use_N_D_index
Use the N-D index instead of the standard 2-D index.

management

Indicate if the AddGeometryColumn and DropGeometryColumn managements functions should be called when adding and dropping the geometry column. Should be set to True for PostGIS 1.x. Default is False. Note that this option has no effect for geoalchemy2.types.Geography.

use_typmod

By default PostgreSQL type modifiers are used to create the geometry column. To use check constraints instead set use_typmod to False. By default this option is not included in the call to AddGeometryColumn. Note that this option is only taken into account if management is set to True and is only available for PostGIS 2.x.
as_binary = None

The name of the “as binary” function for this type. Set in subclasses.

bind_expression(bindvalue)[source]

Specific bind_expression that automatically adds a conversion function

bind_processor(dialect)[source]

Return a conversion function for processing bind values.

Returns a callable which will receive a bind parameter value as the sole positional argument and will return a value to send to the DB-API.

If processing is not necessary, the method should return None.

Parameters:dialect – Dialect instance in use.
column_expression(col)[source]

Specific column_expression that automatically adds a conversion function

comparator_factory

alias of geoalchemy2.comparator.Comparator

from_text = None

The name of “from text” function for this type. Set in subclasses.

name = None

Name used for defining the main geo type (geometry or geography) in CREATE TABLE statements. Set in subclasses.

result_processor(dialect, coltype)[source]

Return a conversion function for processing result row values.

Returns a callable which will receive a result row column value as the sole positional argument and will return a value to return to the user.

If processing is not necessary, the method should return None.

Parameters:
  • dialect – Dialect instance in use.
  • coltype – DBAPI coltype argument received in cursor.description.

Elements

class geoalchemy2.elements.WKTElement(data, srid=-1, extended=False)[source]

Bases: geoalchemy2.elements._SpatialElement

Instances of this class wrap a WKT or EWKT value.

Usage examples:

wkt_element_1 = WKTElement('POINT(5 45)')
wkt_element_2 = WKTElement('POINT(5 45)', srid=4326)
wkt_element_3 = WKTElement('SRID=4326;POINT(5 45)', extended=True)
desc

This element’s description string.

geom_from = 'ST_GeomFromText'
geom_from_extended_version = 'ST_GeomFromEWKT'
class geoalchemy2.elements.WKBElement(data, srid=-1, extended=False)[source]

Bases: geoalchemy2.elements._SpatialElement

Instances of this class wrap a WKB or EWKB value.

Geometry values read from the database are converted to instances of this type. In most cases you won’t need to create WKBElement instances yourself.

If extended is True and srid is -1 at construction time then the SRID will be read from the EWKB data.

Note: you can create WKBElement objects from Shapely geometries using the geoalchemy2.shape.from_shape() function.

desc

This element’s description string.

geom_from = 'ST_GeomFromWKB'
geom_from_extended_version = 'ST_GeomFromEWKB'
class geoalchemy2.elements.RasterElement(data)[source]

Bases: geoalchemy2.elements._SpatialElement

Instances of this class wrap a raster value. Raster values read from the database are converted to instances of this type. In most cases you won’t need to create RasterElement instances yourself.

desc

This element’s description string.

Spatial Functions

This module defines the GenericFunction class, which is the base for the implementation of spatial functions in GeoAlchemy. This module is also where actual spatial functions are defined. Spatial functions supported by GeoAlchemy are defined in this module. See GenericFunction to know how to create new spatial functions.

Note

By convention the names of spatial functions are prefixed by ST_. This is to be consistent with PostGIS’, which itself is based on the SQL-MM standard.

Functions created by subclassing GenericFunction can be called in several ways:

  • By using the func object, which is the SQLAlchemy standard way of calling a function. For example, without the ORM:

    select([func.ST_Area(lake_table.c.geom)])

    and with the ORM:

    Session.query(func.ST_Area(Lake.geom))

  • By applying the function to a geometry column. For example, without the ORM:

    select([lake_table.c.geom.ST_Area()])

    and with the ORM:

    Session.query(Lake.geom.ST_Area())

  • By applying the function to a geoalchemy2.elements.WKBElement object (geoalchemy2.elements.WKBElement is the type into which GeoAlchemy converts geometry values read from the database), or to a geoalchemy2.elements.WKTElement object. For example, without the ORM:

    conn.scalar(lake['geom'].ST_Area())

    and with the ORM:

    session.scalar(lake.geom.ST_Area())

Reference

class geoalchemy2.functions.AddAuth(*args, **kwargs)

Adds an authorization token to be used in the current transaction.

see http://postgis.net/docs/AddAuth.html

class geoalchemy2.functions.AddGeometryColumn(*args, **kwargs)

Adds a geometry column to an existing table.

see http://postgis.net/docs/AddGeometryColumn.html

class geoalchemy2.functions.Box2D(*args, **kwargs)

Returns a BOX2D representing the 2D extent of the geometry.

see http://postgis.net/docs/Box2D_type.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.Box3D(*args, **kwargs)

[geometry] Returns a BOX3D representing the 3D extent of the geometry. OR [raster] Returns the box 3d representation of the enclosing box of the raster.

see http://postgis.net/docs/Box3D_type.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.CheckAuth(*args, **kwargs)

Creates a trigger on a table to prevent/allow updates and deletes of rows based on authorization token.

see http://postgis.net/docs/CheckAuth.html

class geoalchemy2.functions.DisableLongTransactions(*args, **kwargs)

Disables long transaction support.

see http://postgis.net/docs/DisableLongTransactions.html

class geoalchemy2.functions.DropGeometryColumn(*args, **kwargs)

Removes a geometry column from a spatial table.

see http://postgis.net/docs/DropGeometryColumn.html

class geoalchemy2.functions.DropGeometryTable(*args, **kwargs)

Drops a table and all its references in geometry_columns.

see http://postgis.net/docs/DropGeometryTable.html

class geoalchemy2.functions.EnableLongTransactions(*args, **kwargs)

Enables long transaction support.

see http://postgis.net/docs/EnableLongTransactions.html

class geoalchemy2.functions.Find_SRID(*args, **kwargs)

Returns the SRID defined for a geometry column.

see http://postgis.net/docs/Find_SRID.html

class geoalchemy2.functions.GenericFunction(*args, **kwargs)[source]

The base class for GeoAlchemy functions.

This class inherits from sqlalchemy.sql.functions.GenericFunction, so functions defined by subclassing this class can be given a fixed return type. For example, functions like ST_Buffer and ST_Envelope have their type attributes set to geoalchemy2.types.Geometry.

This class allows constructs like Lake.geom.ST_Buffer(2). In that case the Function instance is bound to an expression (Lake.geom here), and that expression is passed to the function when the function is actually called.

If you need to use a function that GeoAlchemy does not provide you will certainly want to subclass this class. For example, if you need the ST_TransScale spatial function, which isn’t (currently) natively supported by GeoAlchemy, you will write this:

from geoalchemy2 import Geometry
from geoalchemy2.functions import GenericFunction

class ST_TransScale(GenericFunction):
    name = 'ST_TransScale'
    type = Geometry
class geoalchemy2.functions.GeometryType(*args, **kwargs)

Returns the type of a geometry as text.

see http://postgis.net/docs/GeometryType.html

class geoalchemy2.functions.LockRow(*args, **kwargs)

Sets lock/authorization for a row in a table.

see http://postgis.net/docs/LockRow.html

class geoalchemy2.functions.Populate_Geometry_Columns(*args, **kwargs)

Ensures geometry columns are defined with type modifiers or have appropriate spatial constraints.

see http://postgis.net/docs/Populate_Geometry_Columns.html

class geoalchemy2.functions.PostGIS_AddBBox(*args, **kwargs)

Add bounding box to the geometry.

see http://postgis.net/docs/PostGIS_AddBBox.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.PostGIS_DropBBox(*args, **kwargs)

Drop the bounding box cache from the geometry.

see http://postgis.net/docs/PostGIS_DropBBox.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.PostGIS_Extensions_Upgrade(*args, **kwargs)

Packages and upgrades postgis extensions (e.g. postgis_raster, postgis_topology, postgis_sfcgal) to latest available version.

see http://postgis.net/docs/PostGIS_Extensions_Upgrade.html

class geoalchemy2.functions.PostGIS_Full_Version(*args, **kwargs)

Reports full postgis version and build configuration infos.

see http://postgis.net/docs/PostGIS_Full_Version.html

class geoalchemy2.functions.PostGIS_GEOS_Version(*args, **kwargs)

Returns the version number of the GEOS library.

see http://postgis.net/docs/PostGIS_GEOS_Version.html

class geoalchemy2.functions.PostGIS_HasBBox(*args, **kwargs)

Returns TRUE if the bbox of this geometry is cached, FALSE otherwise.

see http://postgis.net/docs/PostGIS_HasBBox.html

class geoalchemy2.functions.PostGIS_LibXML_Version(*args, **kwargs)

Returns the version number of the libxml2 library.

see http://postgis.net/docs/PostGIS_LibXML_Version.html

class geoalchemy2.functions.PostGIS_Lib_Build_Date(*args, **kwargs)

Returns build date of the PostGIS library.

see http://postgis.net/docs/PostGIS_Lib_Build_Date.html

class geoalchemy2.functions.PostGIS_Lib_Version(*args, **kwargs)

Returns the version number of the PostGIS library.

see http://postgis.net/docs/PostGIS_Lib_Version.html

class geoalchemy2.functions.PostGIS_Liblwgeom_Version(*args, **kwargs)

Returns the version number of the liblwgeom library. This should match the version of PostGIS.

see http://postgis.net/docs/PostGIS_Liblwgeom_Version.html

class geoalchemy2.functions.PostGIS_PROJ_Version(*args, **kwargs)

Returns the version number of the PROJ4 library.

see http://postgis.net/docs/PostGIS_PROJ_Version.html

class geoalchemy2.functions.PostGIS_Scripts_Build_Date(*args, **kwargs)

Returns build date of the PostGIS scripts.

see http://postgis.net/docs/PostGIS_Scripts_Build_Date.html

class geoalchemy2.functions.PostGIS_Scripts_Installed(*args, **kwargs)

Returns version of the postgis scripts installed in this database.

see http://postgis.net/docs/PostGIS_Scripts_Installed.html

class geoalchemy2.functions.PostGIS_Scripts_Released(*args, **kwargs)

Returns the version number of the postgis.sql script released with the installed postgis lib.

see http://postgis.net/docs/PostGIS_Scripts_Released.html

class geoalchemy2.functions.PostGIS_Version(*args, **kwargs)

Returns PostGIS version number and compile-time options.

see http://postgis.net/docs/PostGIS_Version.html

class geoalchemy2.functions.PostGIS_Wagyu_Version(*args, **kwargs)

Returns the version number of the internal Wagyu library.

see http://postgis.net/docs/PostGIS_Wagyu_Version.html

class geoalchemy2.functions.ST_3DArea(*args, **kwargs)

Computes area of 3D surface geometries. Will return 0 for solids.

see http://postgis.net/docs/ST_3DArea.html

class geoalchemy2.functions.ST_3DClosestPoint(*args, **kwargs)

Returns the 3D point on g1 that is closest to g2. This is the first point of the 3D shortest line.

see http://postgis.net/docs/ST_3DClosestPoint.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_3DDFullyWithin(*args, **kwargs)

Returns true if all of the 3D geometries are within the specified distance of one another.

see http://postgis.net/docs/ST_3DDFullyWithin.html

class geoalchemy2.functions.ST_3DDWithin(*args, **kwargs)

For 3d (z) geometry type Returns true if two geometries 3d distance is within number of units.

see http://postgis.net/docs/ST_3DDWithin.html

class geoalchemy2.functions.ST_3DDifference(*args, **kwargs)

Perform 3D difference

see http://postgis.net/docs/ST_3DDifference.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_3DDistance(*args, **kwargs)

Returns the 3D cartesian minimum distance (based on spatial ref) between two geometries in projected units.

see http://postgis.net/docs/ST_3DDistance.html

class geoalchemy2.functions.ST_3DExtent(*args, **kwargs)

an aggregate function that returns the 3D bounding box that bounds rows of geometries.

see http://postgis.net/docs/ST_3DExtent.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_3DIntersection(*args, **kwargs)

Perform 3D intersection

see http://postgis.net/docs/ST_3DIntersection.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_3DIntersects(*args, **kwargs)

Returns TRUE if the Geometries “spatially intersect” in 3D - only for points, linestrings, polygons, polyhedral surface (area).

see http://postgis.net/docs/ST_3DIntersects.html

class geoalchemy2.functions.ST_3DLength(*args, **kwargs)

Returns the 3D length of a linear geometry.

see http://postgis.net/docs/ST_3DLength.html

class geoalchemy2.functions.ST_3DLineInterpolatePoint(*args, **kwargs)

Returns a point interpolated along a line in 3D. Second argument is a float8 between 0 and 1 representing fraction of total length of linestring the point has to be located.

see http://postgis.net/docs/ST_3DLineInterpolatePoint.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_3DLongestLine(*args, **kwargs)

Returns the 3D longest line between two geometries

see http://postgis.net/docs/ST_3DLongestLine.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_3DMakeBox(*args, **kwargs)

Creates a BOX3D defined by two 3D point geometries.

see http://postgis.net/docs/ST_3DMakeBox.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_3DMaxDistance(*args, **kwargs)

Returns the 3D cartesian maximum distance (based on spatial ref) between two geometries in projected units.

see http://postgis.net/docs/ST_3DMaxDistance.html

class geoalchemy2.functions.ST_3DPerimeter(*args, **kwargs)

Returns the 3D perimeter of a polygonal geometry.

see http://postgis.net/docs/ST_3DPerimeter.html

class geoalchemy2.functions.ST_3DShortestLine(*args, **kwargs)

Returns the 3D shortest line between two geometries

see http://postgis.net/docs/ST_3DShortestLine.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_3DUnion(*args, **kwargs)

Perform 3D union

see http://postgis.net/docs/ST_3DUnion.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_AddBand(*args, **kwargs)

Returns a raster with the new band(s) of given type added with given initial value in the given index location. If no index is specified, the band is added to the end.

see http://postgis.net/docs/RT_ST_AddBand.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_AddMeasure(*args, **kwargs)

Return a derived geometry with measure elements linearly interpolated between the start and end points.

see http://postgis.net/docs/ST_AddMeasure.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_AddPoint(*args, **kwargs)

Add a point to a LineString.

see http://postgis.net/docs/ST_AddPoint.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Affine(*args, **kwargs)

Apply a 3D affine transformation to a geometry.

see http://postgis.net/docs/ST_Affine.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Angle(*args, **kwargs)

Returns the angle between 3 points, or between 2 vectors (4 points or 2 lines).

see http://postgis.net/docs/ST_Angle.html

class geoalchemy2.functions.ST_ApproximateMedialAxis(*args, **kwargs)

Compute the approximate medial axis of an areal geometry.

see http://postgis.net/docs/ST_ApproximateMedialAxis.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Area(*args, **kwargs)

Returns the area of a polygonal geometry.

see http://postgis.net/docs/ST_Area.html

class geoalchemy2.functions.ST_AsBinary(*args, **kwargs)

Return the Well-Known Binary (WKB) representation of the geometry/geography without SRID meta data.

see http://postgis.net/docs/ST_AsBinary.html

class geoalchemy2.functions.ST_AsEWKB(*args, **kwargs)

Return the Well-Known Binary (WKB) representation of the geometry with SRID meta data.

see http://postgis.net/docs/ST_AsEWKB.html

class geoalchemy2.functions.ST_AsEWKT(*args, **kwargs)

Return the Well-Known Text (WKT) representation of the geometry with SRID meta data.

see http://postgis.net/docs/ST_AsEWKT.html

class geoalchemy2.functions.ST_AsEncodedPolyline(*args, **kwargs)

Returns an Encoded Polyline from a LineString geometry.

see http://postgis.net/docs/ST_AsEncodedPolyline.html

class geoalchemy2.functions.ST_AsGDALRaster(*args, **kwargs)

Return the raster tile in the designated GDAL Raster format. Raster formats are one of those supported by your compiled library. Use ST_GDALDrivers() to get a list of formats supported by your library.

see http://postgis.net/docs/RT_ST_AsGDALRaster.html

class geoalchemy2.functions.ST_AsGML(*args, **kwargs)

Return the geometry as a GML version 2 or 3 element.

see http://postgis.net/docs/ST_AsGML.html

class geoalchemy2.functions.ST_AsGeoJSON(*args, **kwargs)[source]

Return the geometry as a GeoJSON “geometry” object, or the row as a GeoJSON feature” object (PostGIS 3 only). (Cf GeoJSON specifications RFC 7946). 2D and 3D Geometries are both supported. GeoJSON only support SFS 1.1 geometry types (no curve support for example). See https://postgis.net/docs/ST_AsGeoJSON.html

class geoalchemy2.functions.ST_AsGeobuf(*args, **kwargs)

Return a Geobuf representation of a set of rows.

see http://postgis.net/docs/ST_AsGeobuf.html

class geoalchemy2.functions.ST_AsHEXEWKB(*args, **kwargs)

Returns a Geometry in HEXEWKB format (as text) using either little-endian (NDR) or big-endian (XDR) encoding.

see http://postgis.net/docs/ST_AsHEXEWKB.html

class geoalchemy2.functions.ST_AsHexWKB(*args, **kwargs)

Return the Well-Known Binary (WKB) in Hex representation of the raster.

see http://postgis.net/docs/RT_ST_AsHexWKB.html

class geoalchemy2.functions.ST_AsJPEG(*args, **kwargs)

Return the raster tile selected bands as a single Joint Photographic Exports Group (JPEG) image (byte array). If no band is specified and 1 or more than 3 bands, then only the first band is used. If only 3 bands then all 3 bands are used and mapped to RGB.

see http://postgis.net/docs/RT_ST_AsJPEG.html

class geoalchemy2.functions.ST_AsKML(*args, **kwargs)

Return the geometry as a KML element. Several variants. Default version=2, default maxdecimaldigits=15

see http://postgis.net/docs/ST_AsKML.html

class geoalchemy2.functions.ST_AsLatLonText(*args, **kwargs)

Return the Degrees, Minutes, Seconds representation of the given point.

see http://postgis.net/docs/ST_AsLatLonText.html

class geoalchemy2.functions.ST_AsMVT(*args, **kwargs)

Aggregate function returning a Mapbox Vector Tile representation of a set of rows.

see http://postgis.net/docs/ST_AsMVT.html

class geoalchemy2.functions.ST_AsMVTGeom(*args, **kwargs)

Transform a geometry into the coordinate space of a Mapbox Vector Tile.

see http://postgis.net/docs/ST_AsMVTGeom.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_AsPNG(*args, **kwargs)

Return the raster tile selected bands as a single portable network graphics (PNG) image (byte array). If 1, 3, or 4 bands in raster and no bands are specified, then all bands are used. If more 2 or more than 4 bands and no bands specified, then only band 1 is used. Bands are mapped to RGB or RGBA space.

see http://postgis.net/docs/RT_ST_AsPNG.html

class geoalchemy2.functions.ST_AsRaster(*args, **kwargs)

Converts a PostGIS geometry to a PostGIS raster.

see http://postgis.net/docs/RT_ST_AsRaster.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_AsSVG(*args, **kwargs)

Returns SVG path data for a geometry.

see http://postgis.net/docs/ST_AsSVG.html

class geoalchemy2.functions.ST_AsTIFF(*args, **kwargs)

Return the raster selected bands as a single TIFF image (byte array). If no band is specified or any of specified bands does not exist in the raster, then will try to use all bands.

see http://postgis.net/docs/RT_ST_AsTIFF.html

class geoalchemy2.functions.ST_AsTWKB(*args, **kwargs)

Returns the geometry as TWKB, aka “Tiny Well-Known Binary”

see http://postgis.net/docs/ST_AsTWKB.html

class geoalchemy2.functions.ST_AsText(*args, **kwargs)

Return the Well-Known Text (WKT) representation of the geometry/geography without SRID metadata.

see http://postgis.net/docs/ST_AsText.html

class geoalchemy2.functions.ST_AsX3D(*args, **kwargs)

Returns a Geometry in X3D xml node element format: ISO-IEC-19776-1.2-X3DEncodings-XML

see http://postgis.net/docs/ST_AsX3D.html

class geoalchemy2.functions.ST_Aspect(*args, **kwargs)

Returns the aspect (in degrees by default) of an elevation raster band. Useful for analyzing terrain.

see http://postgis.net/docs/RT_ST_Aspect.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_Azimuth(*args, **kwargs)

Returns the north-based azimuth as the angle in radians measured clockwise from the vertical on pointA to pointB.

see http://postgis.net/docs/ST_Azimuth.html

class geoalchemy2.functions.ST_Band(*args, **kwargs)

Returns one or more bands of an existing raster as a new raster. Useful for building new rasters from existing rasters.

see http://postgis.net/docs/RT_ST_Band.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_BandFileSize(*args, **kwargs)

Returns the file size of a band stored in file system. If no bandnum specified, 1 is assumed.

see http://postgis.net/docs/RT_ST_BandFileSize.html

class geoalchemy2.functions.ST_BandFileTimestamp(*args, **kwargs)

Returns the file timestamp of a band stored in file system. If no bandnum specified, 1 is assumed.

see http://postgis.net/docs/RT_ST_BandFileTimestamp.html

class geoalchemy2.functions.ST_BandIsNoData(*args, **kwargs)

Returns true if the band is filled with only nodata values.

see http://postgis.net/docs/RT_ST_BandIsNoData.html

class geoalchemy2.functions.ST_BandMetaData(*args, **kwargs)

Returns basic meta data for a specific raster band. band num 1 is assumed if none-specified.

see http://postgis.net/docs/RT_ST_BandMetaData.html

class geoalchemy2.functions.ST_BandNoDataValue(*args, **kwargs)

Returns the value in a given band that represents no data. If no band num 1 is assumed.

see http://postgis.net/docs/RT_ST_BandNoDataValue.html

class geoalchemy2.functions.ST_BandPath(*args, **kwargs)

Returns system file path to a band stored in file system. If no bandnum specified, 1 is assumed.

see http://postgis.net/docs/RT_ST_BandPath.html

class geoalchemy2.functions.ST_BandPixelType(*args, **kwargs)

Returns the type of pixel for given band. If no bandnum specified, 1 is assumed.

see http://postgis.net/docs/RT_ST_BandPixelType.html

class geoalchemy2.functions.ST_BdMPolyFromText(*args, **kwargs)

Construct a MultiPolygon given an arbitrary collection of closed linestrings as a MultiLineString text representation Well-Known text representation.

see http://postgis.net/docs/ST_BdMPolyFromText.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_BdPolyFromText(*args, **kwargs)

Construct a Polygon given an arbitrary collection of closed linestrings as a MultiLineString Well-Known text representation.

see http://postgis.net/docs/ST_BdPolyFromText.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Boundary(*args, **kwargs)

Returns the boundary of a geometry.

see http://postgis.net/docs/ST_Boundary.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_BoundingDiagonal(*args, **kwargs)

Returns the diagonal of a geometry’s bounding box.

see http://postgis.net/docs/ST_BoundingDiagonal.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Box2dFromGeoHash(*args, **kwargs)

Return a BOX2D from a GeoHash string.

see http://postgis.net/docs/ST_Box2dFromGeoHash.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Buffer(*args, **kwargs)
  1. Returns a geometry covering all points within a given distance from the input geometry.

see http://postgis.net/docs/ST_Buffer.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_BuildArea(*args, **kwargs)

Creates an areal geometry formed by the constituent linework of given geometry

see http://postgis.net/docs/ST_BuildArea.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_CPAWithin(*args, **kwargs)

Returns true if the closest point of approach of two trajectories is within the specified distance.

see http://postgis.net/docs/ST_CPAWithin.html

class geoalchemy2.functions.ST_Centroid(*args, **kwargs)

Returns the geometric center of a geometry.

see http://postgis.net/docs/ST_Centroid.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ChaikinSmoothing(*args, **kwargs)

Returns a “smoothed” version of the given geometry using the Chaikin algorithm

see http://postgis.net/docs/ST_ChaikinSmoothing.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Clip(*args, **kwargs)

Returns the raster clipped by the input geometry. If band number not is specified, all bands are processed. If crop is not specified or TRUE, the output raster is cropped.

see http://postgis.net/docs/RT_ST_Clip.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_ClipByBox2D(*args, **kwargs)

Returns the portion of a geometry falling within a rectangle.

see http://postgis.net/docs/ST_ClipByBox2D.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ClosestPoint(*args, **kwargs)

Returns the 2D point on g1 that is closest to g2. This is the first point of the shortest line.

see http://postgis.net/docs/ST_ClosestPoint.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ClosestPointOfApproach(*args, **kwargs)

Returns the measure at which points interpolated along two trajectories are closest.

see http://postgis.net/docs/ST_ClosestPointOfApproach.html

class geoalchemy2.functions.ST_ClusterDBSCAN(*args, **kwargs)

Window function that returns a cluster id for each input geometry using the DBSCAN algorithm.

see http://postgis.net/docs/ST_ClusterDBSCAN.html

class geoalchemy2.functions.ST_ClusterIntersecting(*args, **kwargs)

Aggregate function that clusters the input geometries into connected sets.

see http://postgis.net/docs/ST_ClusterIntersecting.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ClusterKMeans(*args, **kwargs)

Window function that returns a cluster id for each input geometry using the K-means algorithm.

see http://postgis.net/docs/ST_ClusterKMeans.html

class geoalchemy2.functions.ST_ClusterWithin(*args, **kwargs)

Aggregate function that clusters the input geometries by separation distance.

see http://postgis.net/docs/ST_ClusterWithin.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Collect(*args, **kwargs)

Creates a GeometryCollection or Multi* geometry from a set of geometries.

see http://postgis.net/docs/ST_Collect.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_CollectionExtract(*args, **kwargs)

Given a (multi)geometry, return a (multi)geometry consisting only of elements of the specified type.

see http://postgis.net/docs/ST_CollectionExtract.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_CollectionHomogenize(*args, **kwargs)

Given a geometry collection, return the “simplest” representation of the contents.

see http://postgis.net/docs/ST_CollectionHomogenize.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ColorMap(*args, **kwargs)

Creates a new raster of up to four 8BUI bands (grayscale, RGB, RGBA) from the source raster and a specified band. Band 1 is assumed if not specified.

see http://postgis.net/docs/RT_ST_ColorMap.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_ConcaveHull(*args, **kwargs)

The concave hull of a geometry represents a possibly concave geometry that encloses all geometries within the set. You can think of it as shrink wrapping.

see http://postgis.net/docs/ST_ConcaveHull.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ConstrainedDelaunayTriangles(*args, **kwargs)

Return a constrained Delaunay triangulation around the given input geometry.

see http://postgis.net/docs/ST_ConstrainedDelaunayTriangles.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Contains(*args, **kwargs)

[geometry] Returns true if and only if no points of B lie in the exterior of A, and at least one point of the interior of B lies in the interior of A. OR [raster] Return true if no points of raster rastB lie in the exterior of raster rastA and at least one point of the interior of rastB lies in the interior of rastA.

see http://postgis.net/docs/ST_Contains.html

class geoalchemy2.functions.ST_ContainsProperly(*args, **kwargs)

[geometry] Returns true if B intersects the interior of A but not the boundary (or exterior). A does not contain properly itself, but does contain itself. OR [raster] Return true if rastB intersects the interior of rastA but not the boundary or exterior of rastA.

see http://postgis.net/docs/ST_ContainsProperly.html

class geoalchemy2.functions.ST_ConvexHull(*args, **kwargs)

[geometry] Computes the convex hull of a geometry. OR [raster] Return the convex hull geometry of the raster including pixel values equal to BandNoDataValue. For regular shaped and non-skewed rasters, this gives the same result as ST_Envelope so only useful for irregularly shaped or skewed rasters.

see http://postgis.net/docs/ST_ConvexHull.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_CoordDim(*args, **kwargs)

Return the coordinate dimension of a geometry.

see http://postgis.net/docs/ST_CoordDim.html

class geoalchemy2.functions.ST_Count(*args, **kwargs)

Returns the number of pixels in a given band of a raster or raster coverage. If no band is specified defaults to band 1. If exclude_nodata_value is set to true, will only count pixels that are not equal to the nodata value.

see http://postgis.net/docs/RT_ST_Count.html

class geoalchemy2.functions.ST_CountAgg(*args, **kwargs)

Aggregate. Returns the number of pixels in a given band of a set of rasters. If no band is specified defaults to band 1. If exclude_nodata_value is set to true, will only count pixels that are not equal to the NODATA value.

see http://postgis.net/docs/RT_ST_CountAgg.html

class geoalchemy2.functions.ST_CoveredBy(*args, **kwargs)

[geometry] Returns 1 (TRUE) if no point in Geometry/Geography A is outside Geometry/Geography B OR [raster] Return true if no points of raster rastA lie outside raster rastB.

see http://postgis.net/docs/ST_CoveredBy.html

class geoalchemy2.functions.ST_Covers(*args, **kwargs)

[geometry] Returns 1 (TRUE) if no point in Geometry B is outside Geometry A OR [raster] Return true if no points of raster rastB lie outside raster rastA.

see http://postgis.net/docs/ST_Covers.html

class geoalchemy2.functions.ST_Crosses(*args, **kwargs)

Returns TRUE if the supplied geometries have some, but not all, interior points in common.

see http://postgis.net/docs/ST_Crosses.html

class geoalchemy2.functions.ST_CurveToLine(*args, **kwargs)

Converts a CIRCULARSTRING/CURVEPOLYGON/MULTISURFACE to a LINESTRING/POLYGON/MULTIPOLYGON

see http://postgis.net/docs/ST_CurveToLine.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_DFullyWithin(*args, **kwargs)

[geometry] Returns true if all of the geometries are within the specified distance of one another OR [raster] Return true if rasters rastA and rastB are fully within the specified distance of each other.

see http://postgis.net/docs/ST_DFullyWithin.html

class geoalchemy2.functions.ST_DWithin(*args, **kwargs)

[geometry] Returns true if the geometries are within the specified distance of one another. For geometry units are in those of spatial reference and for geography units are in meters and measurement is defaulted to use_spheroid=true (measure around spheroid), for faster check, use_spheroid=false to measure along sphere. OR [raster] Return true if rasters rastA and rastB are within the specified distance of each other.

see http://postgis.net/docs/ST_DWithin.html

class geoalchemy2.functions.ST_DelaunayTriangles(*args, **kwargs)

Return a Delaunay triangulation around the given input points.

see http://postgis.net/docs/ST_DelaunayTriangles.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Difference(*args, **kwargs)

Returns a geometry that represents that part of geometry A that does not intersect with geometry B.

see http://postgis.net/docs/ST_Difference.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Dimension(*args, **kwargs)

Returns the topological dimension of a geometry.

see http://postgis.net/docs/ST_Dimension.html

class geoalchemy2.functions.ST_Disjoint(*args, **kwargs)

[geometry] Returns TRUE if the Geometries do not “spatially intersect” - if they do not share any space together. OR [raster] Return true if raster rastA does not spatially intersect rastB.

see http://postgis.net/docs/ST_Disjoint.html

class geoalchemy2.functions.ST_Distance(*args, **kwargs)

Returns the distance between two geometry or geography values.

see http://postgis.net/docs/ST_Distance.html

class geoalchemy2.functions.ST_DistanceCPA(*args, **kwargs)

Returns the distance between the closest point of approach of two trajectories.

see http://postgis.net/docs/ST_DistanceCPA.html

class geoalchemy2.functions.ST_DistanceSphere(*args, **kwargs)

Returns minimum distance in meters between two lon/lat geometries using a spherical earth model.

see http://postgis.net/docs/ST_DistanceSphere.html

class geoalchemy2.functions.ST_DistanceSpheroid(*args, **kwargs)

Returns the minimum distance between two lon/lat geometries using a spheroidal earth model.

see http://postgis.net/docs/ST_DistanceSpheroid.html

class geoalchemy2.functions.ST_Distance_Sphere(*args, **kwargs)

Returns minimum distance in meters between two lon/lat geometries. Uses a spherical earth and radius of 6370986 meters. Faster than ST_Distance_Spheroid, but less accurate. PostGIS versions prior to 1.5 only implemented for points.

see http://postgis.net/docs/ST_Distance_Sphere.html

class geoalchemy2.functions.ST_Distinct4ma(*args, **kwargs)

Raster processing function that calculates the number of unique pixel values in a neighborhood.

see http://postgis.net/docs/RT_ST_Distinct4ma.html

class geoalchemy2.functions.ST_Dump(*args, **kwargs)

Returns a set of geometry_dump rows for the components of a geometry.

see http://postgis.net/docs/ST_Dump.html

Return type: geoalchemy2.types.GeometryDump.

type

alias of geoalchemy2.types.GeometryDump

class geoalchemy2.functions.ST_DumpAsPolygons(*args, **kwargs)

Returns a set of geomval (geom,val) rows, from a given raster band. If no band number is specified, band num defaults to 1.

see http://postgis.net/docs/RT_ST_DumpAsPolygons.html

class geoalchemy2.functions.ST_DumpPoints(*args, **kwargs)

Returns a set of geometry_dump rows for the points in a geometry.

see http://postgis.net/docs/ST_DumpPoints.html

Return type: geoalchemy2.types.GeometryDump.

type

alias of geoalchemy2.types.GeometryDump

class geoalchemy2.functions.ST_DumpRings(*args, **kwargs)

Returns a set of geometry_dump rows for the exterior and interior rings of a Polygon.

see http://postgis.net/docs/ST_DumpRings.html

Return type: geoalchemy2.types.GeometryDump.

type

alias of geoalchemy2.types.GeometryDump

class geoalchemy2.functions.ST_DumpValues(*args, **kwargs)

Get the values of the specified band as a 2-dimension array.

see http://postgis.net/docs/RT_ST_DumpValues.html

class geoalchemy2.functions.ST_EndPoint(*args, **kwargs)

Returns the last point of a LineString or CircularLineString.

see http://postgis.net/docs/ST_EndPoint.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Envelope(*args, **kwargs)

[geometry] Returns a geometry representing the bounding box of a geometry. OR [raster] Returns the polygon representation of the extent of the raster.

see http://postgis.net/docs/ST_Envelope.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Equals(*args, **kwargs)

Returns true if the given geometries represent the same geometry. Directionality is ignored.

see http://postgis.net/docs/ST_Equals.html

class geoalchemy2.functions.ST_EstimatedExtent(*args, **kwargs)

Return the ‘estimated’ extent of a spatial table.

see http://postgis.net/docs/ST_EstimatedExtent.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Expand(*args, **kwargs)

Returns a bounding box expanded from another bounding box or a geometry.

see http://postgis.net/docs/ST_Expand.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Extent(*args, **kwargs)

an aggregate function that returns the bounding box that bounds rows of geometries.

see http://postgis.net/docs/ST_Extent.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ExteriorRing(*args, **kwargs)

Returns a LineString representing the exterior ring of a Polygon.

see http://postgis.net/docs/ST_ExteriorRing.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Extrude(*args, **kwargs)

Extrude a surface to a related volume

see http://postgis.net/docs/ST_Extrude.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_FilterByM(*args, **kwargs)

Filters vertex points based on their m-value

see http://postgis.net/docs/ST_FilterByM.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_FlipCoordinates(*args, **kwargs)

Returns a version of the given geometry with X and Y axis flipped. Useful for people who have built latitude/longitude features and need to fix them.

see http://postgis.net/docs/ST_FlipCoordinates.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Force2D(*args, **kwargs)

Force the geometries into a “2-dimensional mode”.

see http://postgis.net/docs/ST_Force2D.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Force3D(*args, **kwargs)

Force the geometries into XYZ mode. This is an alias for ST_Force3DZ.

see http://postgis.net/docs/ST_Force_3D.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Force3DM(*args, **kwargs)

Force the geometries into XYM mode.

see http://postgis.net/docs/ST_Force_3DZ.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Force3DZ(*args, **kwargs)

Force the geometries into XYZ mode.

see http://postgis.net/docs/ST_Force_3DZ.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Force4D(*args, **kwargs)

Force the geometries into XYZM mode.

see http://postgis.net/docs/ST_Force_4D.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ForceCollection(*args, **kwargs)

Convert the geometry into a GEOMETRYCOLLECTION.

see http://postgis.net/docs/ST_Force_Collection.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ForceCurve(*args, **kwargs)

Upcast a geometry into its curved type, if applicable.

see http://postgis.net/docs/ST_ForceCurve.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ForceLHR(*args, **kwargs)

Force LHR orientation

see http://postgis.net/docs/ST_ForceLHR.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ForcePolygonCCW(*args, **kwargs)

Orients all exterior rings counter-clockwise and all interior rings clockwise.

see http://postgis.net/docs/ST_ForcePolygonCCW.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ForcePolygonCW(*args, **kwargs)

Orients all exterior rings clockwise and all interior rings counter-clockwise.

see http://postgis.net/docs/ST_ForcePolygonCW.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ForceRHR(*args, **kwargs)

Force the orientation of the vertices in a polygon to follow the Right-Hand-Rule.

see http://postgis.net/docs/ST_ForceRHR.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ForceSFS(*args, **kwargs)

Force the geometries to use SFS 1.1 geometry types only.

see http://postgis.net/docs/ST_ForceSFS.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_FrechetDistance(*args, **kwargs)

Returns the Fréchet distance between two geometries.

see http://postgis.net/docs/ST_FrechetDistance.html

class geoalchemy2.functions.ST_FromGDALRaster(*args, **kwargs)

Returns a raster from a supported GDAL raster file.

see http://postgis.net/docs/RT_ST_FromGDALRaster.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_GMLToSQL(*args, **kwargs)

Return a specified ST_Geometry value from GML representation. This is an alias name for ST_GeomFromGML

see http://postgis.net/docs/ST_GMLToSQL.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeneratePoints(*args, **kwargs)

Converts a polygon or multi-polygon into a multi-point composed of randomly location points within the original areas.

see http://postgis.net/docs/ST_GeneratePoints.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeoHash(*args, **kwargs)

Return a GeoHash representation of the geometry.

see http://postgis.net/docs/ST_GeoHash.html

class geoalchemy2.functions.ST_GeoReference(*args, **kwargs)

Returns the georeference meta data in GDAL or ESRI format as commonly seen in a world file. Default is GDAL.

see http://postgis.net/docs/RT_ST_GeoReference.html

class geoalchemy2.functions.ST_GeogFromText(*args, **kwargs)

Return a specified geography value from Well-Known Text representation or extended (WKT).

see http://postgis.net/docs/ST_GeogFromText.html

Return type: geoalchemy2.types.Geography.

type

alias of geoalchemy2.types.Geography

class geoalchemy2.functions.ST_GeogFromWKB(*args, **kwargs)

Creates a geography instance from a Well-Known Binary geometry representation (WKB) or extended Well Known Binary (EWKB).

see http://postgis.net/docs/ST_GeogFromWKB.html

Return type: geoalchemy2.types.Geography.

type

alias of geoalchemy2.types.Geography

class geoalchemy2.functions.ST_GeographyFromText(*args, **kwargs)

Return a specified geography value from Well-Known Text representation or extended (WKT).

see http://postgis.net/docs/ST_GeographyFromText.html

Return type: geoalchemy2.types.Geography.

type

alias of geoalchemy2.types.Geography

class geoalchemy2.functions.ST_GeomCollFromText(*args, **kwargs)

Makes a collection Geometry from collection WKT with the given SRID. If SRID is not given, it defaults to 0.

see http://postgis.net/docs/ST_GeomCollFromText.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeomFromEWKB(*args, **kwargs)

Return a specified ST_Geometry value from Extended Well-Known Binary representation (EWKB).

see http://postgis.net/docs/ST_GeomFromEWKB.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeomFromEWKT(*args, **kwargs)

Return a specified ST_Geometry value from Extended Well-Known Text representation (EWKT).

see http://postgis.net/docs/ST_GeomFromEWKT.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeomFromGML(*args, **kwargs)

Takes as input GML representation of geometry and outputs a PostGIS geometry object

see http://postgis.net/docs/ST_GeomFromGML.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeomFromGeoHash(*args, **kwargs)

Return a geometry from a GeoHash string.

see http://postgis.net/docs/ST_GeomFromGeoHash.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeomFromGeoJSON(*args, **kwargs)

Takes as input a geojson representation of a geometry and outputs a PostGIS geometry object

see http://postgis.net/docs/ST_GeomFromGeoJSON.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeomFromKML(*args, **kwargs)

Takes as input KML representation of geometry and outputs a PostGIS geometry object

see http://postgis.net/docs/ST_GeomFromKML.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeomFromTWKB(*args, **kwargs)

Creates a geometry instance from a TWKB (“Tiny Well-Known Binary”) geometry representation.

see http://postgis.net/docs/ST_GeomFromTWKB.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeomFromText(*args, **kwargs)

Return a specified ST_Geometry value from Well-Known Text representation (WKT).

see http://postgis.net/docs/ST_GeomFromText.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeomFromWKB(*args, **kwargs)

Creates a geometry instance from a Well-Known Binary geometry representation (WKB) and optional SRID.

see http://postgis.net/docs/ST_GeomFromWKB.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeometricMedian(*args, **kwargs)

Returns the geometric median of a MultiPoint.

see http://postgis.net/docs/ST_GeometricMedian.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeometryFromText(*args, **kwargs)

Return a specified ST_Geometry value from Well-Known Text representation (WKT). This is an alias name for ST_GeomFromText

see http://postgis.net/docs/ST_GeometryFromText.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeometryN(*args, **kwargs)

Return the Nth geometry element of a geometry collection.

see http://postgis.net/docs/ST_GeometryN.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_GeometryType(*args, **kwargs)

Returns the SQL-MM type of a geometry as text.

see http://postgis.net/docs/ST_GeometryType.html

class geoalchemy2.functions.ST_Grayscale(*args, **kwargs)

Creates a new one-8BUI band raster from the source raster and specified bands representing Red, Green and Blue

see http://postgis.net/docs/RT_ST_Grayscale.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_HasArc(*args, **kwargs)

Tests if a geometry contains a circular arc

see http://postgis.net/docs/ST_HasArc.html

class geoalchemy2.functions.ST_HasNoBand(*args, **kwargs)

Returns true if there is no band with given band number. If no band number is specified, then band number 1 is assumed.

see http://postgis.net/docs/RT_ST_HasNoBand.html

class geoalchemy2.functions.ST_HausdorffDistance(*args, **kwargs)

Returns the Hausdorff distance between two geometries.

see http://postgis.net/docs/ST_HausdorffDistance.html

class geoalchemy2.functions.ST_Height(*args, **kwargs)

Returns the height of the raster in pixels.

see http://postgis.net/docs/RT_ST_Height.html

class geoalchemy2.functions.ST_HillShade(*args, **kwargs)

Returns the hypothetical illumination of an elevation raster band using provided azimuth, altitude, brightness and scale inputs.

see http://postgis.net/docs/RT_ST_HillShade.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_Histogram(*args, **kwargs)

Returns a set of record summarizing a raster or raster coverage data distribution separate bin ranges. Number of bins are autocomputed if not specified.

see http://postgis.net/docs/RT_ST_Histogram.html

class geoalchemy2.functions.ST_InteriorRingN(*args, **kwargs)

Returns the Nth interior ring (hole) of a Polygon.

see http://postgis.net/docs/ST_InteriorRingN.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_InterpolatePoint(*args, **kwargs)

Return the value of the measure dimension of a geometry at the point closed to the provided point.

see http://postgis.net/docs/ST_InterpolatePoint.html

class geoalchemy2.functions.ST_Intersection(*args, **kwargs)

[geometry] (T) Returns a geometry that represents the shared portion of geomA and geomB. OR [raster] Returns a raster or a set of geometry-pixelvalue pairs representing the shared portion of two rasters or the geometrical intersection of a vectorization of the raster and a geometry.

see http://postgis.net/docs/ST_Intersection.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Intersects(*args, **kwargs)

[geometry] Returns TRUE if the Geometries/Geography “spatially intersect in 2D” - (share any portion of space) and FALSE if they don’t (they are Disjoint). For geography tolerance is 0.00001 meters (so any points that close are considered to intersect) OR [raster] Return true if raster rastA spatially intersects raster rastB.

see http://postgis.net/docs/ST_Intersects.html

class geoalchemy2.functions.ST_InvDistWeight4ma(*args, **kwargs)

Raster processing function that interpolates a pixel’s value from the pixel’s neighborhood.

see http://postgis.net/docs/RT_ST_InvDistWeight4ma.html

class geoalchemy2.functions.ST_IsClosed(*args, **kwargs)

Tests if a LineStrings’s start and end points are coincident. For a PolyhedralSurface tests if it is closed (volumetric).

see http://postgis.net/docs/ST_IsClosed.html

class geoalchemy2.functions.ST_IsCollection(*args, **kwargs)

Tests if a geometry is a geometry collection type.

see http://postgis.net/docs/ST_IsCollection.html

class geoalchemy2.functions.ST_IsEmpty(*args, **kwargs)

[geometry] Tests if a geometry is empty. OR [raster] Returns true if the raster is empty (width = 0 and height = 0). Otherwise, returns false.

see http://postgis.net/docs/ST_IsEmpty.html

class geoalchemy2.functions.ST_IsPlanar(*args, **kwargs)

Check if a surface is or not planar

see http://postgis.net/docs/ST_IsPlanar.html

class geoalchemy2.functions.ST_IsPolygonCCW(*args, **kwargs)

Tests if Polygons have exterior rings oriented counter-clockwise and interior rings oriented clockwise.

see http://postgis.net/docs/ST_IsPolygonCCW.html

class geoalchemy2.functions.ST_IsPolygonCW(*args, **kwargs)

Tests if Polygons have exterior rings oriented clockwise and interior rings oriented counter-clockwise.

see http://postgis.net/docs/ST_IsPolygonCW.html

class geoalchemy2.functions.ST_IsRing(*args, **kwargs)

Tests if a LineString is closed and simple.

see http://postgis.net/docs/ST_IsRing.html

class geoalchemy2.functions.ST_IsSimple(*args, **kwargs)

Tests if a geometry has no points of self-intersection or self-tangency.

see http://postgis.net/docs/ST_IsSimple.html

class geoalchemy2.functions.ST_IsSolid(*args, **kwargs)

Test if the geometry is a solid. No validity check is performed.

see http://postgis.net/docs/ST_IsSolid.html

class geoalchemy2.functions.ST_IsValid(*args, **kwargs)

Tests if a geometry is well-formed in 2D.

see http://postgis.net/docs/ST_IsValid.html

class geoalchemy2.functions.ST_IsValidDetail(*args, **kwargs)

Returns a valid_detail row stating if a geometry is valid, and if not a reason why and a location.

see http://postgis.net/docs/ST_IsValidDetail.html

class geoalchemy2.functions.ST_IsValidReason(*args, **kwargs)

Returns text stating if a geometry is valid, or a reason for invalidity.

see http://postgis.net/docs/ST_IsValidReason.html

class geoalchemy2.functions.ST_IsValidTrajectory(*args, **kwargs)

Returns true if the geometry is a valid trajectory.

see http://postgis.net/docs/ST_IsValidTrajectory.html

class geoalchemy2.functions.ST_Length(*args, **kwargs)

Returns the 2D length of a linear geometry.

see http://postgis.net/docs/ST_Length.html

class geoalchemy2.functions.ST_Length2D(*args, **kwargs)

Returns the 2D length of a linear geometry. Alias for ST_Length

see http://postgis.net/docs/ST_Length2D.html

class geoalchemy2.functions.ST_LengthSpheroid(*args, **kwargs)

Returns the 2D or 3D length/perimeter of a lon/lat geometry on a spheroid.

see http://postgis.net/docs/ST_LengthSpheroid.html

class geoalchemy2.functions.ST_LineCrossingDirection(*args, **kwargs)

Given 2 linestrings, returns a number between -3 and 3 denoting what kind of crossing behavior. 0 is no crossing.

see http://postgis.net/docs/ST_LineCrossingDirection.html

class geoalchemy2.functions.ST_LineFromEncodedPolyline(*args, **kwargs)

Creates a LineString from an Encoded Polyline.

see http://postgis.net/docs/ST_LineFromEncodedPolyline.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LineFromMultiPoint(*args, **kwargs)

Creates a LineString from a MultiPoint geometry.

see http://postgis.net/docs/ST_LineFromMultiPoint.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LineFromText(*args, **kwargs)

Makes a Geometry from WKT representation with the given SRID. If SRID is not given, it defaults to 0.

see http://postgis.net/docs/ST_LineFromText.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LineFromWKB(*args, **kwargs)

Makes a LINESTRING from WKB with the given SRID

see http://postgis.net/docs/ST_LineFromWKB.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LineInterpolatePoint(*args, **kwargs)

Returns a point interpolated along a line. Second argument is a float8 between 0 and 1 representing fraction of total length of linestring the point has to be located.

see http://postgis.net/docs/ST_LineInterpolatePoint.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LineInterpolatePoints(*args, **kwargs)

Returns one or more points interpolated along a line.

see http://postgis.net/docs/ST_LineInterpolatePoints.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LineLocatePoint(*args, **kwargs)

Returns a float between 0 and 1 representing the location of the closest point on LineString to the given Point, as a fraction of total 2d line length.

see http://postgis.net/docs/ST_LineLocatePoint.html

class geoalchemy2.functions.ST_LineMerge(*args, **kwargs)

Return a (set of) LineString(s) formed by sewing together a MULTILINESTRING.

see http://postgis.net/docs/ST_LineMerge.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LineSubstring(*args, **kwargs)

Return a linestring being a substring of the input one starting and ending at the given fractions of total 2d length. Second and third arguments are float8 values between 0 and 1.

see http://postgis.net/docs/ST_LineSubstring.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LineToCurve(*args, **kwargs)

Converts a LINESTRING/POLYGON to a CIRCULARSTRING, CURVEPOLYGON

see http://postgis.net/docs/ST_LineToCurve.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LinestringFromWKB(*args, **kwargs)

Makes a geometry from WKB with the given SRID.

see http://postgis.net/docs/ST_LinestringFromWKB.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LocateAlong(*args, **kwargs)

Return a derived geometry collection value with elements that match the specified measure. Polygonal elements are not supported.

see http://postgis.net/docs/ST_LocateAlong.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LocateBetween(*args, **kwargs)

Return a derived geometry collection value with elements that match the specified range of measures inclusively.

see http://postgis.net/docs/ST_LocateBetween.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LocateBetweenElevations(*args, **kwargs)

Return a derived geometry (collection) value with elements that intersect the specified range of elevations inclusively.

see http://postgis.net/docs/ST_LocateBetweenElevations.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_LongestLine(*args, **kwargs)

Returns the 2D longest line between two geometries.

see http://postgis.net/docs/ST_LongestLine.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_M(*args, **kwargs)

Returns the M coordinate of a Point.

see http://postgis.net/docs/ST_M.html

class geoalchemy2.functions.ST_MLineFromText(*args, **kwargs)

Return a specified ST_MultiLineString value from WKT representation.

see http://postgis.net/docs/ST_MLineFromText.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MPointFromText(*args, **kwargs)

Makes a Geometry from WKT with the given SRID. If SRID is not given, it defaults to 0.

see http://postgis.net/docs/ST_MPointFromText.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MPolyFromText(*args, **kwargs)

Makes a MultiPolygon Geometry from WKT with the given SRID. If SRID is not given, it defaults to 0.

see http://postgis.net/docs/ST_MPolyFromText.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MakeBox2D(*args, **kwargs)

Creates a BOX2D defined by two 2D point geometries.

see http://postgis.net/docs/ST_MakeBox2D.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MakeEmptyCoverage(*args, **kwargs)

Cover georeferenced area with a grid of empty raster tiles.

see http://postgis.net/docs/RT_ST_MakeEmptyCoverage.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_MakeEmptyRaster(*args, **kwargs)

Returns an empty raster (having no bands) of given dimensions (width & height), upperleft X and Y, pixel size and rotation (scalex, scaley, skewx & skewy) and reference system (srid). If a raster is passed in, returns a new raster with the same size, alignment and SRID. If srid is left out, the spatial ref is set to unknown (0).

see http://postgis.net/docs/RT_ST_MakeEmptyRaster.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_MakeEnvelope(*args, **kwargs)

Creates a rectangular Polygon from minimum and maximum coordinates.

see http://postgis.net/docs/ST_MakeEnvelope.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MakeLine(*args, **kwargs)

Creates a Linestring from Point, MultiPoint, or LineString geometries.

see http://postgis.net/docs/ST_MakeLine.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MakePoint(*args, **kwargs)

Creates a 2D, 3DZ or 4D Point.

see http://postgis.net/docs/ST_MakePoint.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MakePointM(*args, **kwargs)

Creates a Point from X, Y and M values.

see http://postgis.net/docs/ST_MakePointM.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MakePolygon(*args, **kwargs)

Creates a Polygon from a shell and optional list of holes.

see http://postgis.net/docs/ST_MakePolygon.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MakeSolid(*args, **kwargs)

Cast the geometry into a solid. No check is performed. To obtain a valid solid, the input geometry must be a closed Polyhedral Surface or a closed TIN.

see http://postgis.net/docs/ST_MakeSolid.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MakeValid(*args, **kwargs)

Attempts to make an invalid geometry valid without losing vertices.

see http://postgis.net/docs/ST_MakeValid.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MapAlgebra(*args, **kwargs)

[raster] Callback function version - Returns a one-band raster given one or more input rasters, band indexes and one user-specified callback function. OR [raster] Expression version - Returns a one-band raster given one or two input rasters, band indexes and one or more user-specified SQL expressions.

see http://postgis.net/docs/RT_ST_MapAlgebra.html

class geoalchemy2.functions.ST_MapAlgebraExpr(*args, **kwargs)

[raster] 1 raster band version: Creates a new one band raster formed by applying a valid PostgreSQL algebraic operation on the input raster band and of pixeltype provided. Band 1 is assumed if no band is specified. OR [raster] 2 raster band version: Creates a new one band raster formed by applying a valid PostgreSQL algebraic operation on the two input raster bands and of pixeltype provided. band 1 of each raster is assumed if no band numbers are specified. The resulting raster will be aligned (scale, skew and pixel corners) on the grid defined by the first raster and have its extent defined by the “extenttype” parameter. Values for “extenttype” can be: INTERSECTION, UNION, FIRST, SECOND.

see http://postgis.net/docs/RT_ST_MapAlgebraExpr.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_MapAlgebraFct(*args, **kwargs)

[raster] 1 band version - Creates a new one band raster formed by applying a valid PostgreSQL function on the input raster band and of pixeltype prodived. Band 1 is assumed if no band is specified. OR [raster] 2 band version - Creates a new one band raster formed by applying a valid PostgreSQL function on the 2 input raster bands and of pixeltype prodived. Band 1 is assumed if no band is specified. Extent type defaults to INTERSECTION if not specified.

see http://postgis.net/docs/RT_ST_MapAlgebraFct.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_MapAlgebraFctNgb(*args, **kwargs)

1-band version: Map Algebra Nearest Neighbor using user-defined PostgreSQL function. Return a raster which values are the result of a PLPGSQL user function involving a neighborhood of values from the input raster band.

see http://postgis.net/docs/RT_ST_MapAlgebraFctNgb.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_Max4ma(*args, **kwargs)

Raster processing function that calculates the maximum pixel value in a neighborhood.

see http://postgis.net/docs/RT_ST_Max4ma.html

class geoalchemy2.functions.ST_MaxDistance(*args, **kwargs)

Returns the 2D largest distance between two geometries in projected units.

see http://postgis.net/docs/ST_MaxDistance.html

class geoalchemy2.functions.ST_Mean4ma(*args, **kwargs)

Raster processing function that calculates the mean pixel value in a neighborhood.

see http://postgis.net/docs/RT_ST_Mean4ma.html

class geoalchemy2.functions.ST_MemSize(*args, **kwargs)

[geometry] Returns the amount of memory space a geometry takes. OR [raster] Returns the amount of space (in bytes) the raster takes.

see http://postgis.net/docs/ST_MemSize.html

class geoalchemy2.functions.ST_MemUnion(*args, **kwargs)

Same as ST_Union, only memory-friendly (uses less memory and more processor time).

see http://postgis.net/docs/ST_MemUnion.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MetaData(*args, **kwargs)

Returns basic meta data about a raster object such as pixel size, rotation (skew), upper, lower left, etc.

see http://postgis.net/docs/RT_ST_MetaData.html

class geoalchemy2.functions.ST_Min4ma(*args, **kwargs)

Raster processing function that calculates the minimum pixel value in a neighborhood.

see http://postgis.net/docs/RT_ST_Min4ma.html

class geoalchemy2.functions.ST_MinConvexHull(*args, **kwargs)

Return the convex hull geometry of the raster excluding NODATA pixels.

see http://postgis.net/docs/RT_ST_MinConvexHull.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MinDist4ma(*args, **kwargs)

Raster processing function that returns the minimum distance (in number of pixels) between the pixel of interest and a neighboring pixel with value.

see http://postgis.net/docs/RT_ST_MinDist4ma.html

class geoalchemy2.functions.ST_MinPossibleValue(*args, **kwargs)

Returns the minimum value this pixeltype can store.

see http://postgis.net/docs/ST_MinPossibleValue.html

class geoalchemy2.functions.ST_MinimumBoundingCircle(*args, **kwargs)

Returns the smallest circle polygon that can fully contain a geometry. Default uses 48 segments per quarter circle.

see http://postgis.net/docs/ST_MinimumBoundingCircle.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MinimumBoundingRadius(*args, **kwargs)

Returns the center point and radius of the smallest circle that can fully contain a geometry.

see http://postgis.net/docs/ST_MinimumBoundingRadius.html

class geoalchemy2.functions.ST_MinimumClearance(*args, **kwargs)

Returns the minimum clearance of a geometry, a measure of a geometry’s robustness.

see http://postgis.net/docs/ST_MinimumClearance.html

class geoalchemy2.functions.ST_MinimumClearanceLine(*args, **kwargs)

Returns the two-point LineString spanning a geometry’s minimum clearance.

see http://postgis.net/docs/ST_MinimumClearanceLine.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_MinkowskiSum(*args, **kwargs)

Performs Minkowski sum

see http://postgis.net/docs/ST_MinkowskiSum.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Multi(*args, **kwargs)

Return the geometry as a MULTI* geometry.

see http://postgis.net/docs/ST_Multi.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_NDims(*args, **kwargs)

Returns the coordinate dimension of a geometry.

see http://postgis.net/docs/ST_NDims.html

class geoalchemy2.functions.ST_NPoints(*args, **kwargs)

Returns the number of points (vertices) in a geometry.

see http://postgis.net/docs/ST_NPoints.html

class geoalchemy2.functions.ST_NRings(*args, **kwargs)

Returns the number of rings in a polygonal geometry.

see http://postgis.net/docs/ST_NRings.html

class geoalchemy2.functions.ST_NearestValue(*args, **kwargs)

Returns the nearest non-NODATA value of a given band’s pixel specified by a columnx and rowy or a geometric point expressed in the same spatial reference coordinate system as the raster.

see http://postgis.net/docs/RT_ST_NearestValue.html

class geoalchemy2.functions.ST_Neighborhood(*args, **kwargs)

Returns a 2-D double precision array of the non-NODATA values around a given band’s pixel specified by either a columnX and rowY or a geometric point expressed in the same spatial reference coordinate system as the raster.

see http://postgis.net/docs/RT_ST_Neighborhood.html

class geoalchemy2.functions.ST_Node(*args, **kwargs)

Node a set of linestrings.

see http://postgis.net/docs/ST_Node.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Normalize(*args, **kwargs)

Return the geometry in its canonical form.

see http://postgis.net/docs/ST_Normalize.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_NotSameAlignmentReason(*args, **kwargs)

Returns text stating if rasters are aligned and if not aligned, a reason why.

see http://postgis.net/docs/RT_ST_NotSameAlignmentReason.html

class geoalchemy2.functions.ST_NumBands(*args, **kwargs)

Returns the number of bands in the raster object.

see http://postgis.net/docs/RT_ST_NumBands.html

class geoalchemy2.functions.ST_NumGeometries(*args, **kwargs)

Returns the number of elements in a geometry collection.

see http://postgis.net/docs/ST_NumGeometries.html

class geoalchemy2.functions.ST_NumInteriorRing(*args, **kwargs)

Returns the number of interior rings (holes) of a Polygon. Aias for ST_NumInteriorRings

see http://postgis.net/docs/ST_NumInteriorRing.html

class geoalchemy2.functions.ST_NumInteriorRings(*args, **kwargs)

Returns the number of interior rings (holes) of a Polygon.

see http://postgis.net/docs/ST_NumInteriorRings.html

class geoalchemy2.functions.ST_NumPatches(*args, **kwargs)

Return the number of faces on a Polyhedral Surface. Will return null for non-polyhedral geometries.

see http://postgis.net/docs/ST_NumPatches.html

class geoalchemy2.functions.ST_NumPoints(*args, **kwargs)

Returns the number of points in a LineString or CircularString.

see http://postgis.net/docs/ST_NumPoints.html

class geoalchemy2.functions.ST_OffsetCurve(*args, **kwargs)

Return an offset line at a given distance and side from an input line. Useful for computing parallel lines about a center line

see http://postgis.net/docs/ST_OffsetCurve.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_OrderingEquals(*args, **kwargs)

Returns true if the given geometries represent the same geometry and points are in the same directional order.

see http://postgis.net/docs/ST_OrderingEquals.html

class geoalchemy2.functions.ST_Orientation(*args, **kwargs)

Determine surface orientation

see http://postgis.net/docs/ST_Orientation.html

class geoalchemy2.functions.ST_OrientedEnvelope(*args, **kwargs)

Returns a minimum rotated rectangle enclosing a geometry.

see http://postgis.net/docs/ST_OrientedEnvelope.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Overlaps(*args, **kwargs)

[geometry] Returns TRUE if the Geometries share space, are of the same dimension, but are not completely contained by each other. OR [raster] Return true if raster rastA and rastB intersect but one does not completely contain the other.

see http://postgis.net/docs/ST_Overlaps.html

class geoalchemy2.functions.ST_PatchN(*args, **kwargs)

Returns the Nth geometry (face) of a PolyhedralSurface.

see http://postgis.net/docs/ST_PatchN.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Perimeter(*args, **kwargs)

Returns the length of the boundary of a polygonal geometry or geography.

see http://postgis.net/docs/ST_Perimeter.html

class geoalchemy2.functions.ST_Perimeter2D(*args, **kwargs)

Returns the 2D perimeter of a polygonal geometry. Alias for ST_Perimeter.

see http://postgis.net/docs/ST_Perimeter2D.html

class geoalchemy2.functions.ST_PixelAsCentroid(*args, **kwargs)

Returns the centroid (point geometry) of the area represented by a pixel.

see http://postgis.net/docs/RT_ST_PixelAsCentroid.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_PixelAsCentroids(*args, **kwargs)

Returns the centroid (point geometry) for each pixel of a raster band along with the value, the X and the Y raster coordinates of each pixel. The point geometry is the centroid of the area represented by a pixel.

see http://postgis.net/docs/RT_ST_PixelAsCentroids.html

class geoalchemy2.functions.ST_PixelAsPoint(*args, **kwargs)

Returns a point geometry of the pixel’s upper-left corner.

see http://postgis.net/docs/RT_ST_PixelAsPoint.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_PixelAsPoints(*args, **kwargs)

Returns a point geometry for each pixel of a raster band along with the value, the X and the Y raster coordinates of each pixel. The coordinates of the point geometry are of the pixel’s upper-left corner.

see http://postgis.net/docs/RT_ST_PixelAsPoints.html

class geoalchemy2.functions.ST_PixelAsPolygon(*args, **kwargs)

Returns the polygon geometry that bounds the pixel for a particular row and column.

see http://postgis.net/docs/RT_ST_PixelAsPolygon.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_PixelAsPolygons(*args, **kwargs)

Returns the polygon geometry that bounds every pixel of a raster band along with the value, the X and the Y raster coordinates of each pixel.

see http://postgis.net/docs/RT_ST_PixelAsPolygons.html

class geoalchemy2.functions.ST_PixelHeight(*args, **kwargs)

Returns the pixel height in geometric units of the spatial reference system.

see http://postgis.net/docs/RT_ST_PixelHeight.html

class geoalchemy2.functions.ST_PixelOfValue(*args, **kwargs)

Get the columnx, rowy coordinates of the pixel whose value equals the search value.

see http://postgis.net/docs/RT_ST_PixelOfValue.html

class geoalchemy2.functions.ST_PixelWidth(*args, **kwargs)

Returns the pixel width in geometric units of the spatial reference system.

see http://postgis.net/docs/RT_ST_PixelWidth.html

class geoalchemy2.functions.ST_Point(*args, **kwargs)

Creates a Point with the given coordinate values. Alias for ST_MakePoint.

see http://postgis.net/docs/ST_Point.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_PointFromGeoHash(*args, **kwargs)

Return a point from a GeoHash string.

see http://postgis.net/docs/ST_PointFromGeoHash.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_PointFromText(*args, **kwargs)

Makes a point Geometry from WKT with the given SRID. If SRID is not given, it defaults to unknown.

see http://postgis.net/docs/ST_PointFromText.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_PointFromWKB(*args, **kwargs)

Makes a geometry from WKB with the given SRID

see http://postgis.net/docs/ST_PointFromWKB.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_PointInsideCircle(*args, **kwargs)

Is the point geometry inside the circle defined by center_x, center_y, radius

see http://postgis.net/docs/ST_PointInsideCircle.html

class geoalchemy2.functions.ST_PointN(*args, **kwargs)

Returns the Nth point in the first LineString or circular LineString in a geometry.

see http://postgis.net/docs/ST_PointN.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_PointOnSurface(*args, **kwargs)

Returns a POINT guaranteed to lie on the surface.

see http://postgis.net/docs/ST_PointOnSurface.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Points(*args, **kwargs)

Returns a MultiPoint containing all the coordinates of a geometry.

see http://postgis.net/docs/ST_Points.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Polygon(*args, **kwargs)

[geometry] Creates a Polygon from a LineString with a specified SRID. OR [raster] Returns a multipolygon geometry formed by the union of pixels that have a pixel value that is not no data value. If no band number is specified, band num defaults to 1.

see http://postgis.net/docs/ST_Polygon.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_PolygonFromText(*args, **kwargs)

Makes a Geometry from WKT with the given SRID. If SRID is not given, it defaults to 0.

see http://postgis.net/docs/ST_PolygonFromText.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Polygonize(*args, **kwargs)

Aggregate. Creates a GeometryCollection containing possible polygons formed from the constituent linework of a set of geometries.

see http://postgis.net/docs/ST_Polygonize.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Project(*args, **kwargs)

Returns a point projected from a start point by a distance and bearing (azimuth).

see http://postgis.net/docs/ST_Project.html

Return type: geoalchemy2.types.Geography.

type

alias of geoalchemy2.types.Geography

class geoalchemy2.functions.ST_Quantile(*args, **kwargs)

Compute quantiles for a raster or raster table coverage in the context of the sample or population. Thus, a value could be examined to be at the raster’s 25%, 50%, 75% percentile.

see http://postgis.net/docs/RT_ST_Quantile.html

class geoalchemy2.functions.ST_QuantizeCoordinates(*args, **kwargs)

Sets least significant bits of coordinates to zero

see http://postgis.net/docs/ST_QuantizeCoordinates.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Range4ma(*args, **kwargs)

Raster processing function that calculates the range of pixel values in a neighborhood.

see http://postgis.net/docs/RT_ST_Range4ma.html

class geoalchemy2.functions.ST_RastFromHexWKB(*args, **kwargs)

Return a raster value from a Hex representation of Well-Known Binary (WKB) raster.

see http://postgis.net/docs/RT_ST_RastFromHexWKB.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_RastFromWKB(*args, **kwargs)

Return a raster value from a Well-Known Binary (WKB) raster.

see http://postgis.net/docs/RT_ST_RastFromWKB.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_RasterToWorldCoord(*args, **kwargs)

Returns the raster’s upper left corner as geometric X and Y (longitude and latitude) given a column and row. Column and row starts at 1.

see http://postgis.net/docs/RT_ST_RasterToWorldCoord.html

class geoalchemy2.functions.ST_RasterToWorldCoordX(*args, **kwargs)

Returns the geometric X coordinate upper left of a raster, column and row. Numbering of columns and rows starts at 1.

see http://postgis.net/docs/RT_ST_RasterToWorldCoordX.html

class geoalchemy2.functions.ST_RasterToWorldCoordY(*args, **kwargs)

Returns the geometric Y coordinate upper left corner of a raster, column and row. Numbering of columns and rows starts at 1.

see http://postgis.net/docs/RT_ST_RasterToWorldCoordY.html

class geoalchemy2.functions.ST_Reclass(*args, **kwargs)

Creates a new raster composed of band types reclassified from original. The nband is the band to be changed. If nband is not specified assumed to be 1. All other bands are returned unchanged. Use case: convert a 16BUI band to a 8BUI and so forth for simpler rendering as viewable formats.

see http://postgis.net/docs/RT_ST_Reclass.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_Relate(*args, **kwargs)

Returns true if this Geometry is spatially related to anotherGeometry, by testing for intersections between the Interior, Boundary and Exterior of the two geometries as specified by the values in the intersectionMatrixPattern. If no intersectionMatrixPattern is passed in, then returns the maximum intersectionMatrixPattern that relates the 2 geometries.

see http://postgis.net/docs/ST_Relate.html

class geoalchemy2.functions.ST_RelateMatch(*args, **kwargs)

Returns true if intersectionMattrixPattern1 implies intersectionMatrixPattern2

see http://postgis.net/docs/ST_RelateMatch.html

class geoalchemy2.functions.ST_RemovePoint(*args, **kwargs)

Remove point from a linestring.

see http://postgis.net/docs/ST_RemovePoint.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_RemoveRepeatedPoints(*args, **kwargs)

Returns a version of the given geometry with duplicated points removed.

see http://postgis.net/docs/ST_RemoveRepeatedPoints.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Resample(*args, **kwargs)

Resample a raster using a specified resampling algorithm, new dimensions, an arbitrary grid corner and a set of raster georeferencing attributes defined or borrowed from another raster.

see http://postgis.net/docs/RT_ST_Resample.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_Rescale(*args, **kwargs)

Resample a raster by adjusting only its scale (or pixel size). New pixel values are computed using the NearestNeighbor (english or american spelling), Bilinear, Cubic, CubicSpline or Lanczos resampling algorithm. Default is NearestNeighbor.

see http://postgis.net/docs/RT_ST_Rescale.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_Resize(*args, **kwargs)

Resize a raster to a new width/height

see http://postgis.net/docs/RT_ST_Resize.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_Reskew(*args, **kwargs)

Resample a raster by adjusting only its skew (or rotation parameters). New pixel values are computed using the NearestNeighbor (english or american spelling), Bilinear, Cubic, CubicSpline or Lanczos resampling algorithm. Default is NearestNeighbor.

see http://postgis.net/docs/RT_ST_Reskew.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_Retile(*args, **kwargs)

Return a set of configured tiles from an arbitrarily tiled raster coverage.

see http://postgis.net/docs/RT_ST_Retile.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_Reverse(*args, **kwargs)

Return the geometry with vertex order reversed.

see http://postgis.net/docs/ST_Reverse.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Rotate(*args, **kwargs)

Rotates a geometry about an origin point.

see http://postgis.net/docs/ST_Rotate.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_RotateX(*args, **kwargs)

Rotates a geometry about the X axis.

see http://postgis.net/docs/ST_RotateX.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_RotateY(*args, **kwargs)

Rotates a geometry about the Y axis.

see http://postgis.net/docs/ST_RotateY.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_RotateZ(*args, **kwargs)

Rotates a geometry about the Z axis.

see http://postgis.net/docs/ST_RotateZ.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Rotation(*args, **kwargs)

Returns the rotation of the raster in radian.

see http://postgis.net/docs/RT_ST_Rotation.html

class geoalchemy2.functions.ST_Roughness(*args, **kwargs)

Returns a raster with the calculated “roughness” of a DEM.

see http://postgis.net/docs/RT_ST_Roughness.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_SRID(*args, **kwargs)

[geometry] Returns the spatial reference identifier for the ST_Geometry as defined in spatial_ref_sys table. OR [raster] Returns the spatial reference identifier of the raster as defined in spatial_ref_sys table.

see http://postgis.net/docs/ST_SRID.html

class geoalchemy2.functions.ST_SameAlignment(*args, **kwargs)

Returns true if rasters have same skew, scale, spatial ref, and offset (pixels can be put on same grid without cutting into pixels) and false if they don’t with notice detailing issue.

see http://postgis.net/docs/RT_ST_SameAlignment.html

class geoalchemy2.functions.ST_Scale(*args, **kwargs)

Scales a geometry by given factors.

see http://postgis.net/docs/ST_Scale.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ScaleX(*args, **kwargs)

Returns the X component of the pixel width in units of coordinate reference system.

see http://postgis.net/docs/RT_ST_ScaleX.html

class geoalchemy2.functions.ST_ScaleY(*args, **kwargs)

Returns the Y component of the pixel height in units of coordinate reference system.

see http://postgis.net/docs/RT_ST_ScaleY.html

class geoalchemy2.functions.ST_Segmentize(*args, **kwargs)

Return a modified geometry/geography having no segment longer than the given distance.

see http://postgis.net/docs/ST_Segmentize.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_SetBandIndex(*args, **kwargs)

Update the external band number of an out-db band

see http://postgis.net/docs/RT_ST_SetBandIndex.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_SetBandIsNoData(*args, **kwargs)

Sets the isnodata flag of the band to TRUE.

see http://postgis.net/docs/RT_ST_SetBandIsNoData.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_SetBandNoDataValue(*args, **kwargs)

Sets the value for the given band that represents no data. Band 1 is assumed if no band is specified. To mark a band as having no nodata value, set the nodata value = NULL.

see http://postgis.net/docs/RT_ST_SetBandNoDataValue.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_SetBandPath(*args, **kwargs)

Update the external path and band number of an out-db band

see http://postgis.net/docs/RT_ST_SetBandPath.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_SetEffectiveArea(*args, **kwargs)

Sets the effective area for each vertex, storing the value in the M ordinate. A simplified geometry can then be generated by filtering on the M ordinate.

see http://postgis.net/docs/ST_SetEffectiveArea.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_SetGeoReference(*args, **kwargs)

Set Georeference 6 georeference parameters in a single call. Numbers should be separated by white space. Accepts inputs in GDAL or ESRI format. Default is GDAL.

see http://postgis.net/docs/RT_ST_SetGeoReference.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_SetPoint(*args, **kwargs)

Replace point of a linestring with a given point.

see http://postgis.net/docs/ST_SetPoint.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_SetRotation(*args, **kwargs)

Set the rotation of the raster in radian.

see http://postgis.net/docs/RT_ST_SetRotation.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_SetSRID(*args, **kwargs)

[geometry] Set the SRID on a geometry to a particular integer value. OR [raster] Sets the SRID of a raster to a particular integer srid defined in the spatial_ref_sys table.

see http://postgis.net/docs/ST_SetSRID.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_SetScale(*args, **kwargs)

Sets the X and Y size of pixels in units of coordinate reference system. Number units/pixel width/height.

see http://postgis.net/docs/RT_ST_SetScale.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_SetSkew(*args, **kwargs)

Sets the georeference X and Y skew (or rotation parameter). If only one is passed in, sets X and Y to the same value.

see http://postgis.net/docs/RT_ST_SetSkew.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_SetUpperLeft(*args, **kwargs)

Sets the value of the upper left corner of the pixel of the raster to projected X and Y coordinates.

see http://postgis.net/docs/RT_ST_SetUpperLeft.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_SetValue(*args, **kwargs)

Returns modified raster resulting from setting the value of a given band in a given columnx, rowy pixel or the pixels that intersect a particular geometry. Band numbers start at 1 and assumed to be 1 if not specified.

see http://postgis.net/docs/RT_ST_SetValue.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_SetValues(*args, **kwargs)

Returns modified raster resulting from setting the values of a given band.

see http://postgis.net/docs/RT_ST_SetValues.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_SharedPaths(*args, **kwargs)

Returns a collection containing paths shared by the two input linestrings/multilinestrings.

see http://postgis.net/docs/ST_SharedPaths.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ShiftLongitude(*args, **kwargs)

Toggle geometry coordinates between -180..180 and 0..360 ranges.

see http://postgis.net/docs/ST_Shift_Longitude.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_ShortestLine(*args, **kwargs)

Returns the 2D shortest line between two geometries

see http://postgis.net/docs/ST_ShortestLine.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Simplify(*args, **kwargs)

Returns a “simplified” version of the given geometry using the Douglas-Peucker algorithm.

see http://postgis.net/docs/ST_Simplify.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_SimplifyPreserveTopology(*args, **kwargs)

Returns a “simplified” version of the given geometry using the Douglas-Peucker algorithm. Will avoid creating derived geometries (polygons in particular) that are invalid.

see http://postgis.net/docs/ST_SimplifyPreserveTopology.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_SimplifyVW(*args, **kwargs)

Returns a “simplified” version of the given geometry using the Visvalingam-Whyatt algorithm

see http://postgis.net/docs/ST_SimplifyVW.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_SkewX(*args, **kwargs)

Returns the georeference X skew (or rotation parameter).

see http://postgis.net/docs/RT_ST_SkewX.html

class geoalchemy2.functions.ST_SkewY(*args, **kwargs)

Returns the georeference Y skew (or rotation parameter).

see http://postgis.net/docs/RT_ST_SkewY.html

class geoalchemy2.functions.ST_Slope(*args, **kwargs)

Returns the slope (in degrees by default) of an elevation raster band. Useful for analyzing terrain.

see http://postgis.net/docs/RT_ST_Slope.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_Snap(*args, **kwargs)

Snap segments and vertices of input geometry to vertices of a reference geometry.

see http://postgis.net/docs/ST_Snap.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_SnapToGrid(*args, **kwargs)

[geometry] Snap all points of the input geometry to a regular grid. OR [raster] Resample a raster by snapping it to a grid. New pixel values are computed using the NearestNeighbor (english or american spelling), Bilinear, Cubic, CubicSpline or Lanczos resampling algorithm. Default is NearestNeighbor.

see http://postgis.net/docs/ST_SnapToGrid.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Split(*args, **kwargs)

Returns a collection of geometries resulting by splitting a geometry.

see http://postgis.net/docs/ST_Split.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_StartPoint(*args, **kwargs)

Returns the first point of a LineString.

see http://postgis.net/docs/ST_StartPoint.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_StdDev4ma(*args, **kwargs)

Raster processing function that calculates the standard deviation of pixel values in a neighborhood.

see http://postgis.net/docs/RT_ST_StdDev4ma.html

class geoalchemy2.functions.ST_StraightSkeleton(*args, **kwargs)

Compute a straight skeleton from a geometry

see http://postgis.net/docs/ST_StraightSkeleton.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Subdivide(*args, **kwargs)

Returns a set of geometry where no geometry in the set has more than the specified number of vertices.

see http://postgis.net/docs/ST_Subdivide.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Sum4ma(*args, **kwargs)

Raster processing function that calculates the sum of all pixel values in a neighborhood.

see http://postgis.net/docs/RT_ST_Sum4ma.html

class geoalchemy2.functions.ST_Summary(*args, **kwargs)

[geometry] Returns a text summary of the contents of a geometry. OR [raster] Returns a text summary of the contents of the raster.

see http://postgis.net/docs/ST_Summary.html

class geoalchemy2.functions.ST_SummaryStats(*args, **kwargs)

Returns summarystats consisting of count, sum, mean, stddev, min, max for a given raster band of a raster or raster coverage. Band 1 is assumed is no band is specified.

see http://postgis.net/docs/RT_ST_SummaryStats.html

class geoalchemy2.functions.ST_SummaryStatsAgg(*args, **kwargs)

Aggregate. Returns summarystats consisting of count, sum, mean, stddev, min, max for a given raster band of a set of raster. Band 1 is assumed is no band is specified.

see http://postgis.net/docs/RT_ST_SummaryStatsAgg.html

class geoalchemy2.functions.ST_SwapOrdinates(*args, **kwargs)

Returns a version of the given geometry with given ordinate values swapped.

see http://postgis.net/docs/ST_SwapOrdinates.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_SymDifference(*args, **kwargs)

Returns a geometry that represents the portions of A and B that do not intersect. It is called a symmetric difference because ST_SymDifference(A,B) = ST_SymDifference(B,A).

see http://postgis.net/docs/ST_SymDifference.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_TPI(*args, **kwargs)

Returns a raster with the calculated Topographic Position Index.

see http://postgis.net/docs/RT_ST_TPI.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_TRI(*args, **kwargs)

Returns a raster with the calculated Terrain Ruggedness Index.

see http://postgis.net/docs/RT_ST_TRI.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_Tesselate(*args, **kwargs)

Perform surface Tesselation of a polygon or polyhedralsurface and returns as a TIN or collection of TINS

see http://postgis.net/docs/ST_Tesselate.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Tile(*args, **kwargs)

Returns a set of rasters resulting from the split of the input raster based upon the desired dimensions of the output rasters.

see http://postgis.net/docs/RT_ST_Tile.html

Return type: geoalchemy2.types.Raster.

type

alias of geoalchemy2.types.Raster

class geoalchemy2.functions.ST_TileEnvelope(*args, **kwargs)

Creates a rectangular Polygon in Web Mercator (SRID:3857) using the XYZ tile system.

see http://postgis.net/docs/ST_TileEnvelope.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Touches(*args, **kwargs)

[geometry] Returns TRUE if the geometries have at least one point in common, but their interiors do not intersect. OR [raster] Return true if raster rastA and rastB have at least one point in common but their interiors do not intersect.

see http://postgis.net/docs/ST_Touches.html

class geoalchemy2.functions.ST_TransScale(*args, **kwargs)

Translates and scales a geometry by given offsets and factors.

see http://postgis.net/docs/ST_TransScale.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Transform(*args, **kwargs)

[geometry] Return a new geometry with its coordinates transformed to a different spatial reference system. OR [raster] Reprojects a raster in a known spatial reference system to another known spatial reference system using specified resampling algorithm. Options are NearestNeighbor, Bilinear, Cubic, CubicSpline, Lanczos defaulting to NearestNeighbor.

see http://postgis.net/docs/ST_Transform.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Translate(*args, **kwargs)

Translates a geometry by given offsets.

see http://postgis.net/docs/ST_Translate.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_UnaryUnion(*args, **kwargs)

Like ST_Union, but working at the geometry component level.

see http://postgis.net/docs/ST_UnaryUnion.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Union(*args, **kwargs)

[geometry] Returns a geometry that represents the point set union of the Geometries. OR [raster] Returns the union of a set of raster tiles into a single raster composed of 1 or more bands.

see http://postgis.net/docs/ST_Union.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_UpperLeftX(*args, **kwargs)

Returns the upper left X coordinate of raster in projected spatial ref.

see http://postgis.net/docs/RT_ST_UpperLeftX.html

class geoalchemy2.functions.ST_UpperLeftY(*args, **kwargs)

Returns the upper left Y coordinate of raster in projected spatial ref.

see http://postgis.net/docs/RT_ST_UpperLeftY.html

class geoalchemy2.functions.ST_Value(*args, **kwargs)

Returns the value of a given band in a given columnx, rowy pixel or at a particular geometric point. Band numbers start at 1 and assumed to be 1 if not specified. If exclude_nodata_value is set to false, then all pixels include nodata pixels are considered to intersect and return value. If exclude_nodata_value is not passed in then reads it from metadata of raster.

see http://postgis.net/docs/RT_ST_Value.html

class geoalchemy2.functions.ST_ValueCount(*args, **kwargs)

Returns a set of records containing a pixel band value and count of the number of pixels in a given band of a raster (or a raster coverage) that have a given set of values. If no band is specified defaults to band 1. By default nodata value pixels are not counted. and all other values in the pixel are output and pixel band values are rounded to the nearest integer.

see http://postgis.net/docs/RT_ST_ValueCount.html

class geoalchemy2.functions.ST_Volume(*args, **kwargs)

Computes the volume of a 3D solid. If applied to surface (even closed) geometries will return 0.

see http://postgis.net/docs/ST_Volume.html

class geoalchemy2.functions.ST_VoronoiLines(*args, **kwargs)

Returns the boundaries between the cells of the Voronoi diagram constructed from the vertices of a geometry.

see http://postgis.net/docs/ST_VoronoiLines.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_VoronoiPolygons(*args, **kwargs)

Returns the cells of the Voronoi diagram constructed from the vertices of a geometry.

see http://postgis.net/docs/ST_VoronoiPolygons.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_WKBToSQL(*args, **kwargs)

Return a specified ST_Geometry value from Well-Known Binary representation (WKB). This is an alias name for ST_GeomFromWKB that takes no srid

see http://postgis.net/docs/ST_WKBToSQL.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_WKTToSQL(*args, **kwargs)

Return a specified ST_Geometry value from Well-Known Text representation (WKT). This is an alias name for ST_GeomFromText

see http://postgis.net/docs/ST_WKTToSQL.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_Width(*args, **kwargs)

Returns the width of the raster in pixels.

see http://postgis.net/docs/RT_ST_Width.html

class geoalchemy2.functions.ST_Within(*args, **kwargs)

[geometry] Returns true if the geometry A is completely inside geometry B OR [raster] Return true if no points of raster rastA lie in the exterior of raster rastB and at least one point of the interior of rastA lies in the interior of rastB.

see http://postgis.net/docs/ST_Within.html

class geoalchemy2.functions.ST_WorldToRasterCoord(*args, **kwargs)

Returns the upper left corner as column and row given geometric X and Y (longitude and latitude) or a point geometry expressed in the spatial reference coordinate system of the raster.

see http://postgis.net/docs/RT_ST_WorldToRasterCoord.html

class geoalchemy2.functions.ST_WorldToRasterCoordX(*args, **kwargs)

Returns the column in the raster of the point geometry (pt) or a X and Y world coordinate (xw, yw) represented in world spatial reference system of raster.

see http://postgis.net/docs/RT_ST_WorldToRasterCoordX.html

class geoalchemy2.functions.ST_WorldToRasterCoordY(*args, **kwargs)

Returns the row in the raster of the point geometry (pt) or a X and Y world coordinate (xw, yw) represented in world spatial reference system of raster.

see http://postgis.net/docs/RT_ST_WorldToRasterCoordY.html

class geoalchemy2.functions.ST_WrapX(*args, **kwargs)

Wrap a geometry around an X value.

see http://postgis.net/docs/ST_WrapX.html

Return type: geoalchemy2.types.Geometry.

type

alias of geoalchemy2.types.Geometry

class geoalchemy2.functions.ST_X(*args, **kwargs)

Returns the X coordinate of a Point.

see http://postgis.net/docs/ST_X.html

class geoalchemy2.functions.ST_XMax(*args, **kwargs)

Returns the X maxima of a 2D or 3D bounding box or a geometry.

see http://postgis.net/docs/ST_XMax.html

class geoalchemy2.functions.ST_XMin(*args, **kwargs)

Returns the X minima of a 2D or 3D bounding box or a geometry.

see http://postgis.net/docs/ST_XMin.html

class geoalchemy2.functions.ST_Y(*args, **kwargs)

Returns the Y coordinate of a Point.

see http://postgis.net/docs/ST_Y.html

class geoalchemy2.functions.ST_YMax(*args, **kwargs)

Returns the Y maxima of a 2D or 3D bounding box or a geometry.

see http://postgis.net/docs/ST_YMax.html

class geoalchemy2.functions.ST_YMin(*args, **kwargs)

Returns the Y minima of a 2D or 3D bounding box or a geometry.

see http://postgis.net/docs/ST_YMin.html

class geoalchemy2.functions.ST_Z(*args, **kwargs)

Returns the Z coordinate of a Point.

see http://postgis.net/docs/ST_Z.html

class geoalchemy2.functions.ST_ZMax(*args, **kwargs)

Returns the Z maxima of a 2D or 3D bounding box or a geometry.

see http://postgis.net/docs/ST_ZMax.html

class geoalchemy2.functions.ST_ZMin(*args, **kwargs)

Returns the Z minima of a 2D or 3D bounding box or a geometry.

see http://postgis.net/docs/ST_ZMin.html

class geoalchemy2.functions.ST_Zmflag(*args, **kwargs)

Returns a code indicating the ZM coordinate dimension of a geometry.

see http://postgis.net/docs/ST_Zmflag.html

class geoalchemy2.functions.TableRowElement(selectable)[source]
class geoalchemy2.functions.UnlockRows(*args, **kwargs)

Removes all locks held by an authorization token.

see http://postgis.net/docs/UnlockRows.html

class geoalchemy2.functions.UpdateGeometrySRID(*args, **kwargs)

Updates the SRID of all features in a geometry column, and the table metadata.

see http://postgis.net/docs/UpdateGeometrySRID.html

class geoalchemy2.functions.postgis_sfcgal_version(*args, **kwargs)

Returns the version of SFCGAL in use

see http://postgis.net/docs/postgis_sfcgal_version.html

Spatial Operators

This module defines a Comparator class for use with geometry and geography objects. This is where spatial operators, like &&, &<, are defined. Spatial operators very often apply to the bounding boxes of geometries. For example, geom1 && geom2 indicates if geom1’s bounding box intersects geom2’s.

Examples

Select the objects whose bounding boxes are to the left of the bounding box of POLYGON((-5 45,5 45,5 -45,-5 -45,-5 45)):

select([table]).where(table.c.geom.to_left(
    'POLYGON((-5 45,5 45,5 -45,-5 -45,-5 45))'))

The << and >> operators are a bit specific, because they have corresponding Python operator (__lshift__ and __rshift__). The above SELECT expression can thus be rewritten like this:

select([table]).where(
    table.c.geom << 'POLYGON((-5 45,5 45,5 -45,-5 -45,-5 45))')

Operators can also be used when using the ORM. For example:

Session.query(Cls).filter(
    Cls.geom << 'POLYGON((-5 45,5 45,5 -45,-5 -45,-5 45))')

Now some other examples with the <#> operator.

Select the ten objects that are the closest to POINT(0 0) (typical closed neighbors problem):

select([table]).order_by(table.c.geom.distance_box('POINT(0 0)')).limit(10)

Using the ORM:

Session.query(Cls).order_by(Cls.geom.distance_box('POINT(0 0)')).limit(10)

Reference

class geoalchemy2.comparator.BaseComparator(expr)[source]

Bases: sqlalchemy.sql.type_api.Comparator

A custom comparator base class. It adds the ability to call spatial functions on columns that use this kind of comparator. It also defines functions that map to operators supported by Geometry, Geography and Raster columns.

This comparator is used by the geoalchemy2.types.Raster.

__weakref__

list of weak references to the object (if defined)

intersects(other)[source]

The && operator. A’s BBOX intersects B’s.

overlaps_or_to_left(other)[source]

The &< operator. A’s BBOX overlaps or is to the left of B’s.

overlaps_or_to_right(other)[source]

The &> operator. A’s BBOX overlaps or is to the right of B’s.

class geoalchemy2.comparator.Comparator(expr)[source]

Bases: geoalchemy2.comparator.BaseComparator

A custom comparator class. Used in geoalchemy2.types.Geometry and geoalchemy2.types.Geography.

This is where spatial operators like << and <-> are defined.

__lshift__(other)[source]

The << operator. A’s BBOX is strictly to the left of B’s. Same as to_left, so:

table.c.geom << 'POINT(1 2)'

is the same as:

table.c.geom.to_left('POINT(1 2)')
__rshift__(other)[source]

The >> operator. A’s BBOX is strictly to the left of B’s. Same as to_`right`, so:

table.c.geom >> 'POINT(1 2)'

is the same as:

table.c.geom.to_right('POINT(1 2)')
above(other)[source]

The |>> operator. A’s BBOX is strictly above B’s.

below(other)[source]

The <<| operator. A’s BBOX is strictly below B’s.

contained(other)[source]

The @ operator. A’s BBOX is contained by B’s.

contains(other, **kw)[source]

The ~ operator. A’s BBOX contains B’s.

distance_box(other)[source]

The <#> operator. The distance between bounding box of two geometries.

distance_centroid(other)[source]

The <-> operator. The distance between two points.

overlaps_or_above(other)[source]

The |&> operator. A’s BBOX overlaps or is above B’s.

overlaps_or_below(other)[source]

The &<| operator. A’s BBOX overlaps or is below B’s.

same(other)[source]

The ~= operator. A’s BBOX is the same as B’s.

to_left(other)[source]

The << operator. A’s BBOX is strictly to the left of B’s.

to_right(other)[source]

The >> operator. A’s BBOX is strictly to the right of B’s.

Shapely Integration

Development

The code is available on GitHub: https://github.com/geoalchemy/geoalchemy2.

Contributors:

Many thanks to Mike Bayer for his guidance and support! He also fostered the birth of GeoAlchemy 2.

Indices and tables