Source code for geoalchemy2.shape

This module provides utility functions for integrating with Shapely.

.. note::

    As GeoAlchemy 2 itself has no dependency on `Shapely`, applications using
    functions of this module have to ensure that `Shapely` is available.

import shapely.wkb
import shapely.wkt

from .elements import WKBElement, WKTElement
from .compat import buffer, bytes, str

[docs]def to_shape(element): """ Function to convert a :class:`geoalchemy2.types.SpatialElement` to a Shapely geometry. Example:: lake = Session.query(Lake).get(1) polygon = to_shape(lake.geom) """ assert isinstance(element, (WKBElement, WKTElement)) if isinstance(element, WKBElement): data, hex = (, True) if isinstance(, str) else \ (bytes(, False) return shapely.wkb.loads(data, hex=hex) elif isinstance(element, WKTElement): return shapely.wkt.loads(
[docs]def from_shape(shape, srid=-1): """ Function to convert a Shapely geometry to a :class:`geoalchemy2.types.WKBElement`. Additional arguments: ``srid`` An integer representing the spatial reference system. E.g. 4326. Default value is -1, which means no/unknown reference system. Example:: from shapely.geometry import Point wkb_element = from_shape(Point(5, 45), srid=4326) """ return WKBElement(buffer(shape.wkb), srid=srid)