app/django/contrib/gis/utils/wkt.py
author Madhusudan.C.S <madhusudancs@gmail.com>
Sat, 22 Aug 2009 04:00:56 +0530
changeset 2785 bb6064b9fc9d
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
Added Organization View for GHOP. Along with adding the View, the View is also registered with sitemap in the GHOP module's callback.py

"""
 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)])