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"""Collections of polygons and related utilities."""
import shapely
from shapely.geometry import polygon
from shapely.geometry.base import BaseMultipartGeometry
__all__ = ["MultiPolygon"]
class MultiPolygon(BaseMultipartGeometry):
"""A collection of one or more Polygons.
If component polygons overlap the collection is invalid and some
operations on it may fail.
Parameters
----------
polygons : sequence
A sequence of Polygons, or a sequence of (shell, holes) tuples
where shell is the sequence representation of a linear ring
(see LinearRing) and holes is a sequence of such linear rings.
Attributes
----------
geoms : sequence
A sequence of `Polygon` instances
Examples
--------
Construct a MultiPolygon from a sequence of coordinate tuples
>>> from shapely import MultiPolygon, Polygon
>>> ob = MultiPolygon([
... (
... ((0.0, 0.0), (0.0, 1.0), (1.0, 1.0), (1.0, 0.0)),
... [((0.1,0.1), (0.1,0.2), (0.2,0.2), (0.2,0.1))]
... )
... ])
>>> len(ob.geoms)
1
>>> type(ob.geoms[0]) == Polygon
True
"""
__slots__ = []
def __new__(self, polygons=None):
"""Create a new MultiPolygon geometry."""
if polygons is None:
# allow creation of empty multipolygons, to support unpickling
# TODO better empty constructor
return shapely.from_wkt("MULTIPOLYGON EMPTY")
elif isinstance(polygons, MultiPolygon):
return polygons
polygons = getattr(polygons, "geoms", polygons)
# remove None and empty polygons from list of Polygons
polygons = [p for p in polygons if p]
L = len(polygons)
# Bail immediately if we have no input points.
if L == 0:
return shapely.from_wkt("MULTIPOLYGON EMPTY")
# This function does not accept sequences of MultiPolygons: there is
# no implicit flattening.
if any(isinstance(p, MultiPolygon) for p in polygons):
raise ValueError("Sequences of multi-polygons are not valid arguments")
subs = []
for i in range(L):
ob = polygons[i]
if not isinstance(ob, polygon.Polygon):
shell = ob[0]
if len(ob) > 1:
holes = ob[1]
else:
holes = None
p = polygon.Polygon(shell, holes)
else:
p = polygon.Polygon(ob)
subs.append(p)
return shapely.multipolygons(subs)
@property
def __geo_interface__(self):
"""Return a GeoJSON-like mapping of the MultiPolygon geometry."""
allcoords = []
for geom in self.geoms:
coords = []
coords.append(tuple(geom.exterior.coords))
for hole in geom.interiors:
coords.append(tuple(hole.coords))
allcoords.append(tuple(coords))
return {"type": "MultiPolygon", "coordinates": allcoords}
def svg(self, scale_factor=1.0, fill_color=None, opacity=None):
"""Return group of SVG path elements for the MultiPolygon geometry.
Parameters
----------
scale_factor : float
Multiplication factor for the SVG stroke-width. Default is 1.
fill_color : str, optional
Hex string for fill color. Default is to use "#66cc99" if
geometry is valid, and "#ff3333" if invalid.
opacity : float
Float number between 0 and 1 for color opacity. Default value is 0.6
"""
if self.is_empty:
return "<g />"
if fill_color is None:
fill_color = "#66cc99" if self.is_valid else "#ff3333"
return (
"<g>"
+ "".join(p.svg(scale_factor, fill_color, opacity) for p in self.geoms)
+ "</g>"
)
shapely.lib.registry[6] = MultiPolygon
|
