fr/fr_env/lib/python3.8/site-packages/shapely/geometry/geo.py

206 lines
6.3 KiB
Python
Raw Permalink Normal View History

2021-03-07 12:03:19 +05:30
"""
Geometry factories based on the geo interface
"""
from .point import Point, asPoint
from .linestring import LineString, asLineString
from .polygon import Polygon, asPolygon
from .multipoint import MultiPoint, asMultiPoint
from .multilinestring import MultiLineString, asMultiLineString
from .multipolygon import MultiPolygon, MultiPolygonAdapter
from .collection import GeometryCollection
# numpy is an optional dependency
try:
import numpy as np
except ImportError:
_has_numpy = False
else:
_has_numpy = True
def _is_coordinates_empty(coordinates):
"""Helper to identify if coordinates or subset of coordinates are empty"""
if coordinates is None:
return True
is_numpy_array = _has_numpy and isinstance(coordinates, np.ndarray)
if isinstance(coordinates, (list, tuple)) or is_numpy_array:
if len(coordinates) == 0:
return True
return all(map(_is_coordinates_empty, coordinates))
else:
return False
def _empty_shape_for_no_coordinates(geom_type):
"""Return empty counterpart for geom_type"""
if geom_type == 'point':
return Point()
elif geom_type == 'multipoint':
return MultiPoint()
elif geom_type == 'linestring':
return LineString()
elif geom_type == 'multilinestring':
return MultiLineString()
elif geom_type == 'polygon':
return Polygon()
elif geom_type == 'multipolygon':
return MultiPolygon()
else:
raise ValueError("Unknown geometry type: %s" % geom_type)
def box(minx, miny, maxx, maxy, ccw=True):
"""Returns a rectangular polygon with configurable normal vector"""
coords = [(maxx, miny), (maxx, maxy), (minx, maxy), (minx, miny)]
if not ccw:
coords = coords[::-1]
return Polygon(coords)
def shape(context):
"""
Returns a new, independent geometry with coordinates *copied* from the
context. Changes to the original context will not be reflected in the
geometry object.
Parameters
----------
context :
a GeoJSON-like dict, which provides a "type" member describing the type
of the geometry and "coordinates" member providing a list of coordinates,
or an object which implements __geo_interface__.
Returns
-------
Geometry object
Example
-------
Create a Point from GeoJSON, and then create a copy using __geo_interface__.
>>> context = {'type': 'Point', 'coordinates': [0, 1]}
>>> geom = shape(context)
>>> geom.type == 'Point'
True
>>> geom.wkt
'POINT (0 1)'
>>> geom2 = shape(geom)
>>> geom == geom2
True
"""
if hasattr(context, "__geo_interface__"):
ob = context.__geo_interface__
else:
ob = context
geom_type = ob.get("type").lower()
if 'coordinates' in ob and _is_coordinates_empty(ob['coordinates']):
return _empty_shape_for_no_coordinates(geom_type)
elif geom_type == "point":
return Point(ob["coordinates"])
elif geom_type == "linestring":
return LineString(ob["coordinates"])
elif geom_type == "polygon":
return Polygon(ob["coordinates"][0], ob["coordinates"][1:])
elif geom_type == "multipoint":
return MultiPoint(ob["coordinates"])
elif geom_type == "multilinestring":
return MultiLineString(ob["coordinates"])
elif geom_type == "multipolygon":
return MultiPolygon(ob["coordinates"], context_type='geojson')
elif geom_type == "geometrycollection":
geoms = [shape(g) for g in ob.get("geometries", [])]
return GeometryCollection(geoms)
else:
raise ValueError("Unknown geometry type: %s" % geom_type)
def asShape(context):
"""
Adapts the context to a geometry interface. The coordinates remain
stored in the context, and changes to them will be reflected in the
returned geometry object.
Parameters
----------
context :
a GeoJSON-like dict, which provides a "type" member describing the type
of the geometry and "coordinates" member providing a list of coordinates,
or an object which implements __geo_interface__.
Returns
-------
Geometry object
Notes
-----
The Adapter classes returned by this function trade performance for
reduced storage of coordinate values. In general, the shape() function
should be used instead.
Example
-------
Create a Point and Polygon from GeoJSON, change the coordinates of the Point's
context and show that the corresponding geometry is changed, as well.
>>> point_context = {'type': 'Point', 'coordinates': [0.5, 0.5]}
>>> poly_context = {'type': 'Polygon', 'coordinates': [[[0, 0], [1, 0], [1, 1], [0, 1], [0, 0]]]}
>>> point, poly = asShape(point_context), asShape(poly_context)
>>> poly.intersects(point)
True
>>> point_context['coordinates'][0] = 1.5
>>> poly.intersects(point)
False
"""
if hasattr(context, "__geo_interface__"):
ob = context.__geo_interface__
else:
ob = context
try:
geom_type = ob.get("type").lower()
except AttributeError:
raise ValueError("Context does not provide geo interface")
if geom_type == "point":
return asPoint(ob["coordinates"])
elif geom_type == "linestring":
return asLineString(ob["coordinates"])
elif geom_type == "polygon":
return asPolygon(ob["coordinates"][0], ob["coordinates"][1:])
elif geom_type == "multipoint":
return asMultiPoint(ob["coordinates"])
elif geom_type == "multilinestring":
return asMultiLineString(ob["coordinates"])
elif geom_type == "multipolygon":
return MultiPolygonAdapter(ob["coordinates"], context_type='geojson')
elif geom_type == "geometrycollection":
geoms = [asShape(g) for g in ob.get("geometries", [])]
return GeometryCollection(geoms)
else:
raise ValueError("Unknown geometry type: %s" % geom_type)
def mapping(ob):
"""
Returns a GeoJSON-like mapping from a Geometry or any
object which implements __geo_interface__
Parameters
----------
ob :
An object which implements __geo_interface__.
Returns
-------
dict
Example
-------
>>> pt = Point(0, 0)
>>> mapping(p)
{'type': 'Point', 'coordinates': (0.0, 0.0)}
"""
return ob.__geo_interface__