144 lines
4.3 KiB
Python
144 lines
4.3 KiB
Python
"""Geometry factories based on the geo interface."""
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import numpy as np
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from shapely.errors import GeometryTypeError
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from shapely.geometry.collection import GeometryCollection
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from shapely.geometry.linestring import LineString
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from shapely.geometry.multilinestring import MultiLineString
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from shapely.geometry.multipoint import MultiPoint
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from shapely.geometry.multipolygon import MultiPolygon
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from shapely.geometry.point import Point
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from shapely.geometry.polygon import LinearRing, Polygon
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def _is_coordinates_empty(coordinates):
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"""Identify if coordinates or subset of coordinates are empty."""
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if coordinates is None:
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return True
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if isinstance(coordinates, (list, tuple, np.ndarray)):
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if len(coordinates) == 0:
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return True
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return all(map(_is_coordinates_empty, coordinates))
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else:
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return False
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def _empty_shape_for_no_coordinates(geom_type):
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"""Return empty counterpart for geom_type."""
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if geom_type == "point":
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return Point()
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elif geom_type == "multipoint":
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return MultiPoint()
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elif geom_type == "linestring":
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return LineString()
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elif geom_type == "multilinestring":
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return MultiLineString()
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elif geom_type == "polygon":
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return Polygon()
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elif geom_type == "multipolygon":
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return MultiPolygon()
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else:
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raise GeometryTypeError(f"Unknown geometry type: {geom_type!r}")
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def box(minx, miny, maxx, maxy, ccw=True):
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"""Return a rectangular polygon with configurable normal vector."""
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coords = [(maxx, miny), (maxx, maxy), (minx, maxy), (minx, miny)]
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if not ccw:
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coords = coords[::-1]
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return Polygon(coords)
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def shape(context):
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"""Return a new, independent geometry with coordinates copied from the context.
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Changes to the original context will not be reflected in the geometry
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object.
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Parameters
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----------
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context :
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a GeoJSON-like dict, which provides a "type" member describing the type
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of the geometry and "coordinates" member providing a list of coordinates,
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or an object which implements __geo_interface__.
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Returns
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-------
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Geometry object
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Examples
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--------
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Create a Point from GeoJSON, and then create a copy using __geo_interface__.
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>>> from shapely.geometry import shape
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>>> context = {'type': 'Point', 'coordinates': [0, 1]}
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>>> geom = shape(context)
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>>> geom.geom_type == 'Point'
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True
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>>> geom.wkt
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'POINT (0 1)'
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>>> geom2 = shape(geom)
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>>> geom == geom2
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True
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"""
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if hasattr(context, "__geo_interface__"):
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ob = context.__geo_interface__
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else:
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ob = context
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geom_type = ob.get("type").lower()
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if geom_type == "feature":
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# GeoJSON features must have a 'geometry' field.
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ob = ob["geometry"]
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geom_type = ob.get("type").lower()
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if "coordinates" in ob and _is_coordinates_empty(ob["coordinates"]):
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return _empty_shape_for_no_coordinates(geom_type)
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elif geom_type == "point":
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return Point(ob["coordinates"])
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elif geom_type == "linestring":
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return LineString(ob["coordinates"])
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elif geom_type == "linearring":
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return LinearRing(ob["coordinates"])
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elif geom_type == "polygon":
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return Polygon(ob["coordinates"][0], ob["coordinates"][1:])
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elif geom_type == "multipoint":
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return MultiPoint(ob["coordinates"])
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elif geom_type == "multilinestring":
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return MultiLineString(ob["coordinates"])
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elif geom_type == "multipolygon":
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return MultiPolygon([[c[0], c[1:]] for c in ob["coordinates"]])
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elif geom_type == "geometrycollection":
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geoms = [shape(g) for g in ob.get("geometries", [])]
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return GeometryCollection(geoms)
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else:
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raise GeometryTypeError(f"Unknown geometry type: {geom_type!r}")
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def mapping(ob):
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"""Return a GeoJSON-like mapping.
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Input should be a Geometry or an object which implements __geo_interface__.
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Parameters
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----------
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ob : geometry or object
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An object which implements __geo_interface__.
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Returns
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-------
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dict
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Examples
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--------
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>>> from shapely.geometry import mapping, Point
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>>> pt = Point(0, 0)
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>>> mapping(pt)
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{'type': 'Point', 'coordinates': (0.0, 0.0)}
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"""
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return ob.__geo_interface__
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