233 lines
7.9 KiB
Python
233 lines
7.9 KiB
Python
"""This module defines a ``Comparator`` class for use with geometry and geography objects.
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This is where spatial operators, like ``&&``, ``&<``, are defined.
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Spatial operators very often apply to the bounding boxes of geometries. For
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example, ``geom1 && geom2`` indicates if geom1's bounding box intersects
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geom2's.
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Examples
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--------
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Select the objects whose bounding boxes are to the left of the
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bounding box of ``POLYGON((-5 45,5 45,5 -45,-5 -45,-5 45))``::
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select([table]).where(table.c.geom.to_left(
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'POLYGON((-5 45,5 45,5 -45,-5 -45,-5 45))'))
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The ``<<`` and ``>>`` operators are a bit specific, because they have
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corresponding Python operator (``__lshift__`` and ``__rshift__``). The
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above ``SELECT`` expression can thus be rewritten like this::
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select([table]).where(
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table.c.geom << 'POLYGON((-5 45,5 45,5 -45,-5 -45,-5 45))')
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Operators can also be used when using the ORM. For example::
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Session.query(Cls).filter(
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Cls.geom << 'POLYGON((-5 45,5 45,5 -45,-5 -45,-5 45))')
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Now some other examples with the ``<#>`` operator.
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Select the ten objects that are the closest to ``POINT(0 0)`` (typical
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closed neighbors problem)::
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select([table]).order_by(table.c.geom.distance_box('POINT(0 0)')).limit(10)
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Using the ORM::
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Session.query(Cls).order_by(Cls.geom.distance_box('POINT(0 0)')).limit(10)
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"""
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from typing import Any
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from sqlalchemy import types as sqltypes
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from sqlalchemy.dialects.postgresql import DOUBLE_PRECISION
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from sqlalchemy.sql.elements import ColumnElement
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from sqlalchemy.sql.functions import _FunctionGenerator
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from sqlalchemy.sql.operators import custom_op
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from sqlalchemy.types import UserDefinedType
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from geoalchemy2.elements import WKBElement
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from geoalchemy2.elements import WKTElement
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INTERSECTS: custom_op = custom_op("&&")
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INTERSECTS_ND: custom_op = custom_op("&&&")
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OVERLAPS_OR_TO_LEFT: custom_op = custom_op("&<")
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OVERLAPS_OR_TO_RIGHT: custom_op = custom_op("&>")
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OVERLAPS_OR_BELOW: custom_op = custom_op("&<|")
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TO_LEFT: custom_op = custom_op("<<")
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BELOW: custom_op = custom_op("<<|")
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TO_RIGHT: custom_op = custom_op(">>")
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CONTAINED: custom_op = custom_op("@")
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OVERLAPS_OR_ABOVE: custom_op = custom_op("|&>")
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ABOVE: custom_op = custom_op("|>>")
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CONTAINS: custom_op = custom_op("~")
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SAME: custom_op = custom_op("~=")
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DISTANCE_CENTROID: custom_op = custom_op("<->")
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DISTANCE_BOX: custom_op = custom_op("<#>")
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_COMPARATOR_INPUT_TYPE = str | WKBElement | WKTElement
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class BaseComparator(UserDefinedType.Comparator):
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"""A custom comparator base class.
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It adds the ability to call spatial functions on columns that use this kind of comparator.
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It also defines functions that map to operators supported by ``Geometry``, ``Geography``
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and ``Raster`` columns.
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This comparator is used by the :class:`geoalchemy2.types.Raster`.
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"""
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key = None
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def __getattr__(self, name: str) -> Any:
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# Function names that don't start with "ST_" are rejected.
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# This is not to mess up with SQLAlchemy's use of
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# hasattr/getattr on Column objects.
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if not name.lower().startswith("st_"):
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raise AttributeError(f"Attribute {name} not found")
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# We create our own _FunctionGenerator here, and use it in place of
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# SQLAlchemy's "func" object. This is to be able to "bind" the
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# function to the SQL expression. See also GenericFunction.
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func_ = _FunctionGenerator(expr=self.expr)
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return getattr(func_, name)
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def intersects(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``&&`` operator. A's BBOX intersects B's."""
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return self.operate(INTERSECTS, other, result_type=sqltypes.Boolean)
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def overlaps_or_to_left(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``&<`` operator. A's BBOX overlaps or is to the left of B's."""
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return self.operate(OVERLAPS_OR_TO_LEFT, other, result_type=sqltypes.Boolean)
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def overlaps_or_to_right(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``&>`` operator. A's BBOX overlaps or is to the right of B's."""
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return self.operate(OVERLAPS_OR_TO_RIGHT, other, result_type=sqltypes.Boolean)
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class Comparator(BaseComparator):
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"""A custom comparator class.
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Used in :class:`geoalchemy2.types.Geometry` and :class:`geoalchemy2.types.Geography`.
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This is where spatial operators like ``<<`` and ``<->`` are defined.
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"""
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def overlaps_or_below(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``&<|`` operator.
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A's BBOX overlaps or is below B's.
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"""
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return self.operate(OVERLAPS_OR_BELOW, other, result_type=sqltypes.Boolean)
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def to_left(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``<<`` operator.
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A's BBOX is strictly to the left of B's.
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"""
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return self.operate(TO_LEFT, other, result_type=sqltypes.Boolean)
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def __lshift__(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``<<`` operator.
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A's BBOX is strictly to the left of B's.
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Same as ``to_left``, so::
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table.c.geom << 'POINT(1 2)'
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is the same as::
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table.c.geom.to_left('POINT(1 2)')
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"""
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return self.to_left(other)
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def below(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``<<|`` operator.
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A's BBOX is strictly below B's.
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"""
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return self.operate(BELOW, other, result_type=sqltypes.Boolean)
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def to_right(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``>>`` operator.
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A's BBOX is strictly to the right of B's.
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"""
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return self.operate(TO_RIGHT, other, result_type=sqltypes.Boolean)
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def __rshift__(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``>>`` operator.
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A's BBOX is strictly to the left of B's.
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Same as `to_`right``, so::
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table.c.geom >> 'POINT(1 2)'
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is the same as::
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table.c.geom.to_right('POINT(1 2)')
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"""
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return self.to_right(other)
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def contained(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``@`` operator.
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A's BBOX is contained by B's.
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"""
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return self.operate(CONTAINED, other, result_type=sqltypes.Boolean)
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def overlaps_or_above(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``|&>`` operator.
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A's BBOX overlaps or is above B's.
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"""
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return self.operate(OVERLAPS_OR_ABOVE, other, result_type=sqltypes.Boolean)
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def above(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``|>>`` operator.
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A's BBOX is strictly above B's.
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"""
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return self.operate(ABOVE, other, result_type=sqltypes.Boolean)
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def contains(self, other: _COMPARATOR_INPUT_TYPE, **kw) -> ColumnElement:
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"""The ``~`` operator.
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A's BBOX contains B's.
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"""
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return self.operate(CONTAINS, other, result_type=sqltypes.Boolean)
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def same(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``~=`` operator.
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A's BBOX is the same as B's.
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"""
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return self.operate(SAME, other, result_type=sqltypes.Boolean)
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def distance_centroid(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``<->`` operator.
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The distance between two points.
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"""
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return self.operate(DISTANCE_CENTROID, other, result_type=DOUBLE_PRECISION)
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def distance_box(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``<#>`` operator.
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The distance between bounding box of two geometries.
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"""
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return self.operate(DISTANCE_BOX, other, result_type=DOUBLE_PRECISION)
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def intersects_nd(self, other: _COMPARATOR_INPUT_TYPE) -> ColumnElement:
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"""The ``&&&`` operator.
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This operator returns TRUE if the n-D bounding box of geometry A
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intersects the n-D bounding box of geometry B.
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"""
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return self.operate(INTERSECTS_ND, other, result_type=sqltypes.Boolean)
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