56 lines
1.8 KiB
Python
56 lines
1.8 KiB
Python
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"""
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Utilities for manipulating Geometry WKT.
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"""
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def precision_wkt(geom, prec):
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"""
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Returns WKT text of the geometry according to the given precision (an
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integer or a string). If the precision is an integer, then the decimal
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places of coordinates WKT will be truncated to that number:
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>>> pnt = Point(5, 23)
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>>> pnt.wkt
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'POINT (5.0000000000000000 23.0000000000000000)'
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>>> precision(geom, 1)
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'POINT (5.0 23.0)'
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If the precision is a string, it must be valid Python format string
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(e.g., '%20.7f') -- thus, you should know what you're doing.
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"""
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if isinstance(prec, int):
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num_fmt = '%%.%df' % prec
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elif isinstance(prec, basestring):
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num_fmt = prec
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else:
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raise TypeError
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# TODO: Support 3D geometries.
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coord_fmt = ' '.join([num_fmt, num_fmt])
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def formatted_coords(coords):
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return ','.join([coord_fmt % c[:2] for c in coords])
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def formatted_poly(poly):
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return ','.join(['(%s)' % formatted_coords(r) for r in poly])
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def formatted_geom(g):
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gtype = str(g.geom_type).upper()
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yield '%s(' % gtype
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if gtype == 'POINT':
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yield formatted_coords((g.coords,))
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elif gtype in ('LINESTRING', 'LINEARRING'):
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yield formatted_coords(g.coords)
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elif gtype in ('POLYGON', 'MULTILINESTRING'):
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yield formatted_poly(g)
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elif gtype == 'MULTIPOINT':
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yield formatted_coords(g.coords)
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elif gtype == 'MULTIPOLYGON':
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yield ','.join(['(%s)' % formatted_poly(p) for p in g])
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elif gtype == 'GEOMETRYCOLLECTION':
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yield ','.join([''.join([wkt for wkt in formatted_geom(child)]) for child in g])
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else:
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raise TypeError
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yield ')'
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return ''.join([wkt for wkt in formatted_geom(geom)])
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