def __init__(self, *args, **kwargs):
"""
Initializes on the given sequence -- may take lists, tuples, NumPy arrays
of X,Y pairs, or Point objects. If Point objects are used, ownership is
_not_ transferred to the LineString object.
Examples:
ls = LineString((1, 1), (2, 2))
ls = LineString([(1, 1), (2, 2)])
ls = LineString(array([(1, 1), (2, 2)]))
ls = LineString(Point(1, 1), Point(2, 2))
"""
# If only one argument provided, set the coords array appropriately
if len(args) == 1: coords = args[0]
else: coords = args
if isinstance(coords, (tuple, list)):
# Getting the number of coords and the number of dimensions -- which
# must stay the same, e.g., no LineString((1, 2), (1, 2, 3)).
ncoords = len(coords)
if coords: ndim = len(coords[0])
else: raise TypeError('Cannot initialize on empty sequence.')
self._checkdim(ndim)
# Incrementing through each of the coordinates and verifying
for i in xrange(1, ncoords):
if not isinstance(coords[i], (tuple, list, Point)):
raise TypeError('each coordinate should be a sequence (list or tuple)')
if len(coords[i]) != ndim: raise TypeError('Dimension mismatch.')
numpy_coords = False
elif numpy and isinstance(coords, numpy.ndarray):
shape = coords.shape # Using numpy's shape.
if len(shape) != 2: raise TypeError('Too many dimensions.')
self._checkdim(shape[1])
ncoords = shape[0]
ndim = shape[1]
numpy_coords = True
else:
raise TypeError('Invalid initialization input for LineStrings.')
# Creating a coordinate sequence object because it is easier to
# set the points using GEOSCoordSeq.__setitem__().
cs = GEOSCoordSeq(capi.create_cs(ncoords, ndim), z=bool(ndim==3))
for i in xrange(ncoords):
if numpy_coords: cs[i] = coords[i,:]
elif isinstance(coords[i], Point): cs[i] = coords[i].tuple
else: cs[i] = coords[i]
# If SRID was passed in with the keyword arguments
srid = kwargs.get('srid', None)
# Calling the base geometry initialization with the returned pointer
# from the function.
super(LineString, self).__init__(self._init_func(cs.ptr), srid=srid)
def _create_point(self, ndim, coords):
"""
Create a coordinate sequence, set X, Y, [Z], and create point
"""
if ndim < 2 or ndim > 3:
raise TypeError('Invalid point dimension: %s' % str(ndim))
cs = capi.create_cs(c_uint(1), c_uint(ndim))
i = iter(coords)
capi.cs_setx(cs, 0, i.next())
capi.cs_sety(cs, 0, i.next())
if ndim == 3: capi.cs_setz(cs, 0, i.next())
return capi.create_point(cs)
def _set_list(self, length, items):
ndim = self._cs.dims #
hasz = self._cs.hasz # I don't understand why these are different
# create a new coordinate sequence and populate accordingly
cs = GEOSCoordSeq(capi.create_cs(length, ndim), z=hasz)
for i, c in enumerate(items):
cs[i] = c
ptr = self._init_func(cs.ptr)
if ptr:
capi.destroy_geom(self.ptr)
self.ptr = ptr
self._post_init(self.srid)
else:
# can this happen?
raise GEOSException('Geometry resulting from slice deletion was invalid.')
