68 lines
2.2 KiB
Python
68 lines
2.2 KiB
Python
"""Paths and patches"""
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from matplotlib.patches import PathPatch
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from matplotlib.path import Path
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from numpy import asarray, concatenate, ones
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class Polygon(object):
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# Adapt Shapely or GeoJSON/geo_interface polygons to a common interface
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def __init__(self, context):
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if hasattr(context, 'interiors'):
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self.context = context
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else:
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self.context = getattr(context, '__geo_interface__', context)
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@property
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def geom_type(self):
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return (getattr(self.context, 'geom_type', None)
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or self.context['type'])
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@property
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def exterior(self):
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return (getattr(self.context, 'exterior', None)
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or self.context['coordinates'][0])
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@property
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def interiors(self):
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value = getattr(self.context, 'interiors', None)
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if value is None:
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value = self.context['coordinates'][1:]
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return value
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def PolygonPath(polygon):
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"""Constructs a compound matplotlib path from a Shapely or GeoJSON-like
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geometric object"""
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this = Polygon(polygon)
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assert this.geom_type == 'Polygon'
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def coding(ob):
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# The codes will be all "LINETO" commands, except for "MOVETO"s at the
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# beginning of each subpath
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n = len(getattr(ob, 'coords', None) or ob)
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vals = ones(n, dtype=Path.code_type) * Path.LINETO
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vals[0] = Path.MOVETO
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return vals
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vertices = concatenate([asarray(this.exterior)] + [asarray(r) for r in this.interiors])
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codes = concatenate([coding(this.exterior)] + [coding(r) for r in this.interiors])
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return Path(vertices, codes)
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def PolygonPatch(polygon, **kwargs):
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"""Constructs a matplotlib patch from a geometric object
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The `polygon` may be a Shapely or GeoJSON-like object with or without holes.
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The `kwargs` are those supported by the matplotlib.patches.Polygon class
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constructor. Returns an instance of matplotlib.patches.PathPatch.
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Example (using Shapely Point and a matplotlib axes):
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>>> b = Point(0, 0).buffer(1.0)
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>>> patch = PolygonPatch(b, fc='blue', ec='blue', alpha=0.5)
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>>> axis.add_patch(patch)
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"""
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return PathPatch(PolygonPath(polygon), **kwargs)
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