app/django/contrib/gis/utils/wkt.py
author Madhusudan C.S. <madhusudancs@gmail.com>
Tue, 11 Aug 2009 12:48:10 -0700
changeset 2757 7d0d0ce76bd9
parent 323 ff1a9aa48cfd
permissions -rw-r--r--
updateOrCreateFromFields is made to call updateOrCreateFromKeyName. updateOrCreateFromFields called self._model.get_or_insert which only creates new entities but doesn't update the properties if the entity already exists. So updateOrCreateFromFields is now made to call updateOrCreateFromKeyName which actually updates the entity properties if entity already exists. Reviewed by: Lennard de Rijk

"""
 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)])