"""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)
"""
from typing import Union
from sqlalchemy import types as sqltypes
from sqlalchemy.dialects.postgresql import DOUBLE_PRECISION
from sqlalchemy.sql.elements import ColumnElement
from sqlalchemy.sql.functions import _FunctionGenerator
from sqlalchemy.sql.operators import custom_op
from sqlalchemy.types import UserDefinedType
from geoalchemy2.elements import WKBElement
from geoalchemy2.elements import WKTElement
INTERSECTS: custom_op = custom_op("&&")
INTERSECTS_ND: custom_op = custom_op("&&&")
OVERLAPS_OR_TO_LEFT: custom_op = custom_op("&<")
OVERLAPS_OR_TO_RIGHT: custom_op = custom_op("&>")
OVERLAPS_OR_BELOW: custom_op = custom_op("&<|")
TO_LEFT: custom_op = custom_op("<<")
BELOW: custom_op = custom_op("<<|")
TO_RIGHT: custom_op = custom_op(">>")
CONTAINED: custom_op = custom_op("@")
OVERLAPS_OR_ABOVE: custom_op = custom_op("|&>")
ABOVE: custom_op = custom_op("|>>")
CONTAINS: custom_op = custom_op("~")
SAME: custom_op = custom_op("~=")
DISTANCE_CENTROID: custom_op = custom_op("<->")
DISTANCE_BOX: custom_op = custom_op("<#>")
_COMPARATOR_INPUT_TYPE = Union[str, WKBElement, WKTElement]
[docs]
class BaseComparator(UserDefinedType.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 :class:`geoalchemy2.types.Raster`.
"""
key = None
def __getattr__(self, name):
# Function names that don't start with "ST_" are rejected.
# This is not to mess up with SQLAlchemy's use of
# hasattr/getattr on Column objects.
if not name.lower().startswith("st_"):
raise AttributeError
# We create our own _FunctionGenerator here, and use it in place of
# SQLAlchemy's "func" object. This is to be able to "bind" the
# function to the SQL expression. See also GenericFunction.
func_ = _FunctionGenerator(expr=self.expr)
return getattr(func_, name)
[docs]
def intersects(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``&&`` operator. A's BBOX intersects B's."""
return self.operate(INTERSECTS, other, result_type=sqltypes.Boolean)
[docs]
def overlaps_or_to_left(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``&<`` operator. A's BBOX overlaps or is to the left of B's."""
return self.operate(OVERLAPS_OR_TO_LEFT, other, result_type=sqltypes.Boolean)
[docs]
def overlaps_or_to_right(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``&>`` operator. A's BBOX overlaps or is to the right of B's."""
return self.operate(OVERLAPS_OR_TO_RIGHT, other, result_type=sqltypes.Boolean)
[docs]
class Comparator(BaseComparator):
"""A custom comparator class.
Used in :class:`geoalchemy2.types.Geometry` and :class:`geoalchemy2.types.Geography`.
This is where spatial operators like ``<<`` and ``<->`` are defined.
"""
[docs]
def overlaps_or_below(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``&<|`` operator.
A's BBOX overlaps or is below B's.
"""
return self.operate(OVERLAPS_OR_BELOW, other, result_type=sqltypes.Boolean)
[docs]
def to_left(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``<<`` operator.
A's BBOX is strictly to the left of B's.
"""
return self.operate(TO_LEFT, other, result_type=sqltypes.Boolean)
[docs]
def __lshift__(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""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)')
"""
return self.to_left(other)
[docs]
def below(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``<<|`` operator.
A's BBOX is strictly below B's.
"""
return self.operate(BELOW, other, result_type=sqltypes.Boolean)
[docs]
def to_right(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``>>`` operator.
A's BBOX is strictly to the right of B's.
"""
return self.operate(TO_RIGHT, other, result_type=sqltypes.Boolean)
[docs]
def __rshift__(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""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)')
"""
return self.to_right(other)
[docs]
def contained(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``@`` operator.
A's BBOX is contained by B's.
"""
return self.operate(CONTAINED, other, result_type=sqltypes.Boolean)
[docs]
def overlaps_or_above(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``|&>`` operator.
A's BBOX overlaps or is above B's.
"""
return self.operate(OVERLAPS_OR_ABOVE, other, result_type=sqltypes.Boolean)
[docs]
def above(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``|>>`` operator.
A's BBOX is strictly above B's.
"""
return self.operate(ABOVE, other, result_type=sqltypes.Boolean)
[docs]
def contains(self, other: _COMPARATOR_INPUT_TYPE, **kw) -> ColumnElement:
"""The ``~`` operator.
A's BBOX contains B's.
"""
return self.operate(CONTAINS, other, result_type=sqltypes.Boolean)
[docs]
def same(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``~=`` operator.
A's BBOX is the same as B's.
"""
return self.operate(SAME, other, result_type=sqltypes.Boolean)
[docs]
def distance_centroid(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``<->`` operator.
The distance between two points.
"""
return self.operate(DISTANCE_CENTROID, other, result_type=DOUBLE_PRECISION)
[docs]
def distance_box(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``<#>`` operator.
The distance between bounding box of two geometries.
"""
return self.operate(DISTANCE_BOX, other, result_type=DOUBLE_PRECISION)
[docs]
def intersects_nd(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
"""The ``&&&`` operator.
This operator returns TRUE if the n-D bounding box of geometry A
intersects the n-D bounding box of geometry B.
"""
return self.operate(INTERSECTS_ND, other, result_type=sqltypes.Boolean)
