django1/django/contrib/gis/geos/coordseq.py

165 lines
5.6 KiB
Python

"""
This module houses the GEOSCoordSeq object, which is used internally
by GEOSGeometry to house the actual coordinates of the Point,
LineString, and LinearRing geometries.
"""
from ctypes import c_double, c_uint, byref
from types import ListType, TupleType
from django.contrib.gis.geos.error import GEOSException, GEOSIndexError
from django.contrib.gis.geos.libgeos import CS_PTR, HAS_NUMPY
from django.contrib.gis.geos.prototypes import cs_clone, cs_getdims, cs_getordinate, cs_getsize, cs_setordinate
if HAS_NUMPY: from numpy import ndarray
class GEOSCoordSeq(object):
"The internal representation of a list of coordinates inside a Geometry."
#### Python 'magic' routines ####
def __init__(self, ptr, z=False):
"Initializes from a GEOS pointer."
if not isinstance(ptr, CS_PTR):
raise TypeError('Coordinate sequence should initialize with a CS_PTR.')
self._ptr = ptr
self._z = z
def __iter__(self):
"Iterates over each point in the coordinate sequence."
for i in xrange(self.size):
yield self[i]
def __len__(self):
"Returns the number of points in the coordinate sequence."
return int(self.size)
def __str__(self):
"Returns the string representation of the coordinate sequence."
return str(self.tuple)
def __getitem__(self, index):
"Returns the coordinate sequence value at the given index."
coords = [self.getX(index), self.getY(index)]
if self.dims == 3 and self._z:
coords.append(self.getZ(index))
return tuple(coords)
def __setitem__(self, index, value):
"Sets the coordinate sequence value at the given index."
# Checking the input value
if isinstance(value, (ListType, TupleType)):
pass
elif HAS_NUMPY and isinstance(value, ndarray):
pass
else:
raise TypeError('Must set coordinate with a sequence (list, tuple, or numpy array).')
# Checking the dims of the input
if self.dims == 3 and self._z:
n_args = 3
set_3d = True
else:
n_args = 2
set_3d = False
if len(value) != n_args:
raise TypeError('Dimension of value does not match.')
# Setting the X, Y, Z
self.setX(index, value[0])
self.setY(index, value[1])
if set_3d: self.setZ(index, value[2])
#### Internal Routines ####
def _checkindex(self, index):
"Checks the given index."
sz = self.size
if (sz < 1) or (index < 0) or (index >= sz):
raise GEOSIndexError('invalid GEOS Geometry index: %s' % str(index))
def _checkdim(self, dim):
"Checks the given dimension."
if dim < 0 or dim > 2:
raise GEOSException('invalid ordinate dimension "%d"' % dim)
@property
def ptr(self):
"""
Property for controlling access to coordinate sequence pointer,
preventing attempted access to a NULL memory location.
"""
if self._ptr: return self._ptr
else: raise GEOSException('NULL coordinate sequence pointer encountered.')
#### Ordinate getting and setting routines ####
def getOrdinate(self, dimension, index):
"Returns the value for the given dimension and index."
self._checkindex(index)
self._checkdim(dimension)
return cs_getordinate(self.ptr, index, dimension, byref(c_double()))
def setOrdinate(self, dimension, index, value):
"Sets the value for the given dimension and index."
self._checkindex(index)
self._checkdim(dimension)
cs_setordinate(self.ptr, index, dimension, value)
def getX(self, index):
"Get the X value at the index."
return self.getOrdinate(0, index)
def setX(self, index, value):
"Set X with the value at the given index."
self.setOrdinate(0, index, value)
def getY(self, index):
"Get the Y value at the given index."
return self.getOrdinate(1, index)
def setY(self, index, value):
"Set Y with the value at the given index."
self.setOrdinate(1, index, value)
def getZ(self, index):
"Get Z with the value at the given index."
return self.getOrdinate(2, index)
def setZ(self, index, value):
"Set Z with the value at the given index."
self.setOrdinate(2, index, value)
### Dimensions ###
@property
def size(self):
"Returns the size of this coordinate sequence."
return cs_getsize(self.ptr, byref(c_uint()))
@property
def dims(self):
"Returns the dimensions of this coordinate sequence."
return cs_getdims(self.ptr, byref(c_uint()))
@property
def hasz(self):
"""
Returns whether this coordinate sequence is 3D. This property value is
inherited from the parent Geometry.
"""
return self._z
### Other Methods ###
def clone(self):
"Clones this coordinate sequence."
return GEOSCoordSeq(cs_clone(self.ptr), self.hasz)
@property
def kml(self):
"Returns the KML representation for the coordinates."
# Getting the substitution string depending on whether the coordinates have
# a Z dimension.
if self.hasz: substr = '%s,%s,%s '
else: substr = '%s,%s,0 '
return '<coordinates>%s</coordinates>' % \
''.join([substr % self[i] for i in xrange(len(self))]).strip()
@property
def tuple(self):
"Returns a tuple version of this coordinate sequence."
n = self.size
if n == 1: return self[0]
else: return tuple([self[i] for i in xrange(n)])