153 lines
5.4 KiB
Python
153 lines
5.4 KiB
Python
from django.contrib.gis.geos.base import numpy
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from django.contrib.gis.geos.coordseq import GEOSCoordSeq
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from django.contrib.gis.geos.error import GEOSException
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from django.contrib.gis.geos.geometry import GEOSGeometry
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from django.contrib.gis.geos.point import Point
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from django.contrib.gis.geos import prototypes as capi
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class LineString(GEOSGeometry):
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_init_func = capi.create_linestring
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_minlength = 2
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#### Python 'magic' routines ####
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def __init__(self, *args, **kwargs):
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"""
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Initializes on the given sequence -- may take lists, tuples, NumPy arrays
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of X,Y pairs, or Point objects. If Point objects are used, ownership is
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_not_ transferred to the LineString object.
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Examples:
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ls = LineString((1, 1), (2, 2))
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ls = LineString([(1, 1), (2, 2)])
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ls = LineString(array([(1, 1), (2, 2)]))
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ls = LineString(Point(1, 1), Point(2, 2))
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"""
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# If only one argument provided, set the coords array appropriately
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if len(args) == 1: coords = args[0]
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else: coords = args
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if isinstance(coords, (tuple, list)):
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# Getting the number of coords and the number of dimensions -- which
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# must stay the same, e.g., no LineString((1, 2), (1, 2, 3)).
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ncoords = len(coords)
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if coords: ndim = len(coords[0])
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else: raise TypeError('Cannot initialize on empty sequence.')
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self._checkdim(ndim)
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# Incrementing through each of the coordinates and verifying
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for i in xrange(1, ncoords):
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if not isinstance(coords[i], (tuple, list, Point)):
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raise TypeError('each coordinate should be a sequence (list or tuple)')
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if len(coords[i]) != ndim: raise TypeError('Dimension mismatch.')
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numpy_coords = False
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elif numpy and isinstance(coords, numpy.ndarray):
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shape = coords.shape # Using numpy's shape.
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if len(shape) != 2: raise TypeError('Too many dimensions.')
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self._checkdim(shape[1])
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ncoords = shape[0]
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ndim = shape[1]
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numpy_coords = True
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else:
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raise TypeError('Invalid initialization input for LineStrings.')
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# Creating a coordinate sequence object because it is easier to
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# set the points using GEOSCoordSeq.__setitem__().
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cs = GEOSCoordSeq(capi.create_cs(ncoords, ndim), z=bool(ndim==3))
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for i in xrange(ncoords):
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if numpy_coords: cs[i] = coords[i,:]
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elif isinstance(coords[i], Point): cs[i] = coords[i].tuple
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else: cs[i] = coords[i]
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# If SRID was passed in with the keyword arguments
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srid = kwargs.get('srid', None)
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# Calling the base geometry initialization with the returned pointer
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# from the function.
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super(LineString, self).__init__(self._init_func(cs.ptr), srid=srid)
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def __iter__(self):
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"Allows iteration over this LineString."
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for i in xrange(len(self)):
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yield self[i]
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def __len__(self):
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"Returns the number of points in this LineString."
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return len(self._cs)
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def _get_single_external(self, index):
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return self._cs[index]
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_get_single_internal = _get_single_external
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def _set_list(self, length, items):
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ndim = self._cs.dims #
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hasz = self._cs.hasz # I don't understand why these are different
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# create a new coordinate sequence and populate accordingly
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cs = GEOSCoordSeq(capi.create_cs(length, ndim), z=hasz)
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for i, c in enumerate(items):
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cs[i] = c
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ptr = self._init_func(cs.ptr)
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if ptr:
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capi.destroy_geom(self.ptr)
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self.ptr = ptr
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self._post_init(self.srid)
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else:
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# can this happen?
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raise GEOSException('Geometry resulting from slice deletion was invalid.')
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def _set_single(self, index, value):
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self._checkindex(index)
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self._cs[index] = value
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def _checkdim(self, dim):
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if dim not in (2, 3): raise TypeError('Dimension mismatch.')
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#### Sequence Properties ####
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@property
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def tuple(self):
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"Returns a tuple version of the geometry from the coordinate sequence."
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return self._cs.tuple
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coords = tuple
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def _listarr(self, func):
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"""
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Internal routine that returns a sequence (list) corresponding with
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the given function. Will return a numpy array if possible.
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"""
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lst = [func(i) for i in xrange(len(self))]
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if numpy: return numpy.array(lst) # ARRRR!
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else: return lst
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@property
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def array(self):
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"Returns a numpy array for the LineString."
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return self._listarr(self._cs.__getitem__)
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@property
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def merged(self):
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"Returns the line merge of this LineString."
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return self._topology(capi.geos_linemerge(self.ptr))
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@property
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def x(self):
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"Returns a list or numpy array of the X variable."
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return self._listarr(self._cs.getX)
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@property
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def y(self):
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"Returns a list or numpy array of the Y variable."
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return self._listarr(self._cs.getY)
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@property
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def z(self):
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"Returns a list or numpy array of the Z variable."
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if not self.hasz: return None
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else: return self._listarr(self._cs.getZ)
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# LinearRings are LineStrings used within Polygons.
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class LinearRing(LineString):
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_minLength = 4
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_init_func = capi.create_linearring
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