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