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  • Documentation version: 1.10

Source code for django.contrib.gis.geos.geometry

 This module contains the 'base' GEOSGeometry object -- all GEOS Geometries
 inherit from this object.
from __future__ import unicode_literals

import json
import warnings
from ctypes import addressof, byref, c_double

from django.contrib.gis import gdal
from django.contrib.gis.geometry.regex import hex_regex, json_regex, wkt_regex
from django.contrib.gis.geos import prototypes as capi
from django.contrib.gis.geos.base import GEOSBase
from django.contrib.gis.geos.coordseq import GEOSCoordSeq
from django.contrib.gis.geos.error import GEOSException
from django.contrib.gis.geos.libgeos import GEOM_PTR
from django.contrib.gis.geos.mutable_list import ListMixin
from django.contrib.gis.geos.prepared import PreparedGeometry
from django.contrib.gis.geos.prototypes.io import (
    ewkb_w, wkb_r, wkb_w, wkt_r, wkt_w,
from django.utils import six
from django.utils.deconstruct import deconstructible
from django.utils.deprecation import RemovedInDjango20Warning
from django.utils.encoding import force_bytes, force_text

[docs]@deconstructible class GEOSGeometry(GEOSBase, ListMixin): "A class that, generally, encapsulates a GEOS geometry." _GEOS_CLASSES = None ptr_type = GEOM_PTR has_cs = False # Only Point, LineString, LinearRing have coordinate sequences def __init__(self, geo_input, srid=None): """ The base constructor for GEOS geometry objects, and may take the following inputs: * strings: - WKT - HEXEWKB (a PostGIS-specific canonical form) - GeoJSON (requires GDAL) * buffer: - WKB The `srid` keyword is used to specify the Source Reference Identifier (SRID) number for this Geometry. If not set, the SRID will be None. """ if isinstance(geo_input, bytes): geo_input = force_text(geo_input) if isinstance(geo_input, six.string_types): wkt_m = wkt_regex.match(geo_input) if wkt_m: # Handling WKT input. if wkt_m.group('srid'): srid = int(wkt_m.group('srid')) g = wkt_r().read(force_bytes(wkt_m.group('wkt'))) elif hex_regex.match(geo_input): # Handling HEXEWKB input. g = wkb_r().read(force_bytes(geo_input)) elif json_regex.match(geo_input): # Handling GeoJSON input. if not gdal.HAS_GDAL: raise ValueError('Initializing geometry from JSON input requires GDAL.') g = wkb_r().read(gdal.OGRGeometry(geo_input).wkb) else: raise ValueError('String or unicode input unrecognized as WKT EWKT, and HEXEWKB.') elif isinstance(geo_input, GEOM_PTR): # When the input is a pointer to a geometry (GEOM_PTR). g = geo_input elif isinstance(geo_input, six.memoryview): # When the input is a buffer (WKB). g = wkb_r().read(geo_input) elif isinstance(geo_input, GEOSGeometry): g = capi.geom_clone(geo_input.ptr) else: # Invalid geometry type. raise TypeError('Improper geometry input type: %s' % str(type(geo_input))) if g: # Setting the pointer object with a valid pointer. self.ptr = g else: raise GEOSException('Could not initialize GEOS Geometry with given input.') # Post-initialization setup. self._post_init(srid) def _post_init(self, srid): "Helper routine for performing post-initialization setup." # Setting the SRID, if given. if srid and isinstance(srid, int): self.srid = srid # Setting the class type (e.g., Point, Polygon, etc.) if GEOSGeometry._GEOS_CLASSES is None: # Lazy-loaded variable to avoid import conflicts with GEOSGeometry. from .linestring import LineString, LinearRing from .point import Point from .polygon import Polygon from .collections import ( GeometryCollection, MultiPoint, MultiLineString, MultiPolygon) GEOSGeometry._GEOS_CLASSES = { 0: Point, 1: LineString, 2: LinearRing, 3: Polygon, 4: MultiPoint, 5: MultiLineString, 6: MultiPolygon, 7: GeometryCollection, } self.__class__ = GEOSGeometry._GEOS_CLASSES[self.geom_typeid] # Setting the coordinate sequence for the geometry (will be None on # geometries that do not have coordinate sequences) self._set_cs() def __del__(self): """ Destroys this Geometry; in other words, frees the memory used by the GEOS C++ object. """ try: capi.destroy_geom(self._ptr) except (AttributeError, TypeError): pass # Some part might already have been garbage collected def __copy__(self): """ Returns a clone because the copy of a GEOSGeometry may contain an invalid pointer location if the original is garbage collected. """ return self.clone() def __deepcopy__(self, memodict): """ The `deepcopy` routine is used by the `Node` class of django.utils.tree; thus, the protocol routine needs to be implemented to return correct copies (clones) of these GEOS objects, which use C pointers. """ return self.clone() def __str__(self): "EWKT is used for the string representation." return self.ewkt def __repr__(self): "Short-hand representation because WKT may be very large." return '<%s object at %s>' % (self.geom_type, hex(addressof(self.ptr))) # Pickling support def __getstate__(self): # The pickled state is simply a tuple of the WKB (in string form) # and the SRID. return bytes(self.wkb), self.srid def __setstate__(self, state): # Instantiating from the tuple state that was pickled. wkb, srid = state ptr = wkb_r().read(six.memoryview(wkb)) if not ptr: raise GEOSException('Invalid Geometry loaded from pickled state.') self.ptr = ptr self._post_init(srid) # Comparison operators def __eq__(self, other): """ Equivalence testing, a Geometry may be compared with another Geometry or a WKT representation. """ if isinstance(other, six.string_types): return self.wkt == other elif isinstance(other, GEOSGeometry): return self.equals_exact(other) else: return False def __ne__(self, other): "The not equals operator." return not (self == other) # ### Geometry set-like operations ### # Thanks to Sean Gillies for inspiration: # http://lists.gispython.org/pipermail/community/2007-July/001034.html # g = g1 | g2 def __or__(self, other): "Returns the union of this Geometry and the other." return self.union(other) # g = g1 & g2 def __and__(self, other): "Returns the intersection of this Geometry and the other." return self.intersection(other) # g = g1 - g2 def __sub__(self, other): "Return the difference this Geometry and the other." return self.difference(other) # g = g1 ^ g2 def __xor__(self, other): "Return the symmetric difference of this Geometry and the other." return self.sym_difference(other) # #### Coordinate Sequence Routines #### def _set_cs(self): "Sets the coordinate sequence for this Geometry." if self.has_cs: self._cs = GEOSCoordSeq(capi.get_cs(self.ptr), self.hasz) else: self._cs = None @property def coord_seq(self): "Returns a clone of the coordinate sequence for this Geometry." if self.has_cs: return self._cs.clone() # #### Geometry Info #### @property def geom_type(self): "Returns a string representing the Geometry type, e.g. 'Polygon'" return capi.geos_type(self.ptr).decode() @property def geom_typeid(self): "Returns an integer representing the Geometry type." return capi.geos_typeid(self.ptr) @property def num_geom(self): "Returns the number of geometries in the Geometry." return capi.get_num_geoms(self.ptr) @property def num_coords(self): "Returns the number of coordinates in the Geometry." return capi.get_num_coords(self.ptr) @property def num_points(self): "Returns the number points, or coordinates, in the Geometry." return self.num_coords @property def dims(self): "Returns the dimension of this Geometry (0=point, 1=line, 2=surface)." return capi.get_dims(self.ptr) def normalize(self): "Converts this Geometry to normal form (or canonical form)." return capi.geos_normalize(self.ptr) # #### Unary predicates #### @property def empty(self): """ Returns a boolean indicating whether the set of points in this Geometry are empty. """ return capi.geos_isempty(self.ptr) @property def hasz(self): "Returns whether the geometry has a 3D dimension." return capi.geos_hasz(self.ptr) @property def ring(self): "Returns whether or not the geometry is a ring." return capi.geos_isring(self.ptr) @property def simple(self): "Returns false if the Geometry not simple." return capi.geos_issimple(self.ptr) @property def valid(self): "This property tests the validity of this Geometry." return capi.geos_isvalid(self.ptr) @property def valid_reason(self): """ Returns a string containing the reason for any invalidity. """ return capi.geos_isvalidreason(self.ptr).decode() # #### Binary predicates. ####
[docs] def contains(self, other): "Returns true if other.within(this) returns true." return capi.geos_contains(self.ptr, other.ptr)
[docs] def covers(self, other): """ Return True if the DE-9IM Intersection Matrix for the two geometries is T*****FF*, *T****FF*, ***T**FF*, or ****T*FF*. If either geometry is empty, return False. """ return capi.geos_covers(self.ptr, other.ptr)
[docs] def crosses(self, other): """ Returns true if the DE-9IM intersection matrix for the two Geometries is T*T****** (for a point and a curve,a point and an area or a line and an area) 0******** (for two curves). """ return capi.geos_crosses(self.ptr, other.ptr)
[docs] def disjoint(self, other): """ Returns true if the DE-9IM intersection matrix for the two Geometries is FF*FF****. """ return capi.geos_disjoint(self.ptr, other.ptr)
[docs] def equals(self, other): """ Returns true if the DE-9IM intersection matrix for the two Geometries is T*F**FFF*. """ return capi.geos_equals(self.ptr, other.ptr)
[docs] def equals_exact(self, other, tolerance=0): """ Returns true if the two Geometries are exactly equal, up to a specified tolerance. """ return capi.geos_equalsexact(self.ptr, other.ptr, float(tolerance))
[docs] def intersects(self, other): "Returns true if disjoint returns false." return capi.geos_intersects(self.ptr, other.ptr)
[docs] def overlaps(self, other): """ Returns true if the DE-9IM intersection matrix for the two Geometries is T*T***T** (for two points or two surfaces) 1*T***T** (for two curves). """ return capi.geos_overlaps(self.ptr, other.ptr)
[docs] def relate_pattern(self, other, pattern): """ Returns true if the elements in the DE-9IM intersection matrix for the two Geometries match the elements in pattern. """ if not isinstance(pattern, six.string_types) or len(pattern) > 9: raise GEOSException('invalid intersection matrix pattern') return capi.geos_relatepattern(self.ptr, other.ptr, force_bytes(pattern))
[docs] def touches(self, other): """ Returns true if the DE-9IM intersection matrix for the two Geometries is FT*******, F**T***** or F***T****. """ return capi.geos_touches(self.ptr, other.ptr)
[docs] def within(self, other): """ Returns true if the DE-9IM intersection matrix for the two Geometries is T*F**F***. """ return capi.geos_within(self.ptr, other.ptr)
# #### SRID Routines #### @property def srid(self): "Gets the SRID for the geometry, returns None if no SRID is set." s = capi.geos_get_srid(self.ptr) if s == 0: return None else: return s @srid.setter def srid(self, srid): "Sets the SRID for the geometry." capi.geos_set_srid(self.ptr, 0 if srid is None else srid) def get_srid(self): warnings.warn( "`get_srid()` is deprecated, use the `srid` property instead.", RemovedInDjango20Warning, 2 ) return self.srid def set_srid(self, srid): warnings.warn( "`set_srid()` is deprecated, use the `srid` property instead.", RemovedInDjango20Warning, 2 ) self.srid = srid # #### Output Routines #### @property def ewkt(self): """ Returns the EWKT (SRID + WKT) of the Geometry. """ srid = self.srid return 'SRID=%s;%s' % (srid, self.wkt) if srid else self.wkt @property def wkt(self): "Returns the WKT (Well-Known Text) representation of this Geometry." return wkt_w(dim=3 if self.hasz else 2, trim=True).write(self).decode() @property def hex(self): """ Returns the WKB of this Geometry in hexadecimal form. Please note that the SRID is not included in this representation because it is not a part of the OGC specification (use the `hexewkb` property instead). """ # A possible faster, all-python, implementation: # str(self.wkb).encode('hex') return wkb_w(dim=3 if self.hasz else 2).write_hex(self) @property def hexewkb(self): """ Returns the EWKB of this Geometry in hexadecimal form. This is an extension of the WKB specification that includes SRID value that are a part of this geometry. """ return ewkb_w(dim=3 if self.hasz else 2).write_hex(self) @property def json(self): """ Returns GeoJSON representation of this Geometry. """ return json.dumps({'type': self.__class__.__name__, 'coordinates': self.coords}) geojson = json @property def wkb(self): """ Returns the WKB (Well-Known Binary) representation of this Geometry as a Python buffer. SRID and Z values are not included, use the `ewkb` property instead. """ return wkb_w(3 if self.hasz else 2).write(self) @property def ewkb(self): """ Return the EWKB representation of this Geometry as a Python buffer. This is an extension of the WKB specification that includes any SRID value that are a part of this geometry. """ return ewkb_w(3 if self.hasz else 2).write(self) @property def kml(self): "Returns the KML representation of this Geometry." gtype = self.geom_type return '<%s>%s</%s>' % (gtype, self.coord_seq.kml, gtype) @property def prepared(self): """ Returns a PreparedGeometry corresponding to this geometry -- it is optimized for the contains, intersects, and covers operations. """ return PreparedGeometry(self) # #### GDAL-specific output routines #### @property def ogr(self): "Returns the OGR Geometry for this Geometry." if not gdal.HAS_GDAL: raise GEOSException('GDAL required to convert to an OGRGeometry.') if self.srid: try: return gdal.OGRGeometry(self.wkb, self.srid) except gdal.SRSException: pass return gdal.OGRGeometry(self.wkb) @property def srs(self): "Returns the OSR SpatialReference for SRID of this Geometry." if not gdal.HAS_GDAL: raise GEOSException('GDAL required to return a SpatialReference object.') if self.srid: try: return gdal.SpatialReference(self.srid) except gdal.SRSException: pass return None @property def crs(self): "Alias for `srs` property." return self.srs
[docs] def transform(self, ct, clone=False): """ Requires GDAL. Transforms the geometry according to the given transformation object, which may be an integer SRID, and WKT or PROJ.4 string. By default, the geometry is transformed in-place and nothing is returned. However if the `clone` keyword is set, then this geometry will not be modified and a transformed clone will be returned instead. """ srid = self.srid if ct == srid: # short-circuit where source & dest SRIDs match if clone: return self.clone() else: return if not gdal.HAS_GDAL: raise GEOSException("GDAL library is not available to transform() geometry.") if isinstance(ct, gdal.CoordTransform): # We don't care about SRID because CoordTransform presupposes # source SRS. srid = None elif srid is None or srid < 0: raise GEOSException("Calling transform() with no SRID set is not supported") # Creating an OGR Geometry, which is then transformed. g = gdal.OGRGeometry(self.wkb, srid) g.transform(ct) # Getting a new GEOS pointer ptr = wkb_r().read(g.wkb) if clone: # User wants a cloned transformed geometry returned. return GEOSGeometry(ptr, srid=g.srid) if ptr: # Reassigning pointer, and performing post-initialization setup # again due to the reassignment. capi.destroy_geom(self.ptr) self.ptr = ptr self._post_init(g.srid) else: raise GEOSException('Transformed WKB was invalid.')
# #### Topology Routines #### def _topology(self, gptr): "Helper routine to return Geometry from the given pointer." return GEOSGeometry(gptr, srid=self.srid) @property def boundary(self): "Returns the boundary as a newly allocated Geometry object." return self._topology(capi.geos_boundary(self.ptr))
[docs] def buffer(self, width, quadsegs=8): """ Returns a geometry that represents all points whose distance from this Geometry is less than or equal to distance. Calculations are in the Spatial Reference System of this Geometry. The optional third parameter sets the number of segment used to approximate a quarter circle (defaults to 8). (Text from PostGIS documentation at ch. 6.1.3) """ return self._topology(capi.geos_buffer(self.ptr, width, quadsegs))
@property def centroid(self): """ The centroid is equal to the centroid of the set of component Geometries of highest dimension (since the lower-dimension geometries contribute zero "weight" to the centroid). """ return self._topology(capi.geos_centroid(self.ptr)) @property def convex_hull(self): """ Returns the smallest convex Polygon that contains all the points in the Geometry. """ return self._topology(capi.geos_convexhull(self.ptr))
[docs] def difference(self, other): """ Returns a Geometry representing the points making up this Geometry that do not make up other. """ return self._topology(capi.geos_difference(self.ptr, other.ptr))
@property def envelope(self): "Return the envelope for this geometry (a polygon)." return self._topology(capi.geos_envelope(self.ptr))
[docs] def intersection(self, other): "Returns a Geometry representing the points shared by this Geometry and other." return self._topology(capi.geos_intersection(self.ptr, other.ptr))
@property def point_on_surface(self): "Computes an interior point of this Geometry." return self._topology(capi.geos_pointonsurface(self.ptr))
[docs] def relate(self, other): "Returns the DE-9IM intersection matrix for this Geometry and the other." return capi.geos_relate(self.ptr, other.ptr).decode()
[docs] def simplify(self, tolerance=0.0, preserve_topology=False): """ Returns the Geometry, simplified using the Douglas-Peucker algorithm to the specified tolerance (higher tolerance => less points). If no tolerance provided, defaults to 0. By default, this function does not preserve topology - e.g. polygons can be split, collapse to lines or disappear holes can be created or disappear, and lines can cross. By specifying preserve_topology=True, the result will have the same dimension and number of components as the input. This is significantly slower. """ if preserve_topology: return self._topology(capi.geos_preservesimplify(self.ptr, tolerance)) else: return self._topology(capi.geos_simplify(self.ptr, tolerance))
[docs] def sym_difference(self, other): """ Returns a set combining the points in this Geometry not in other, and the points in other not in this Geometry. """ return self._topology(capi.geos_symdifference(self.ptr, other.ptr))
@property def unary_union(self): "Return the union of all the elements of this geometry." return self._topology(capi.geos_unary_union(self.ptr))
[docs] def union(self, other): "Returns a Geometry representing all the points in this Geometry and other." return self._topology(capi.geos_union(self.ptr, other.ptr))
# #### Other Routines #### @property def area(self): "Returns the area of the Geometry." return capi.geos_area(self.ptr, byref(c_double()))
[docs] def distance(self, other): """ Returns the distance between the closest points on this Geometry and the other. Units will be in those of the coordinate system of the Geometry. """ if not isinstance(other, GEOSGeometry): raise TypeError('distance() works only on other GEOS Geometries.') return capi.geos_distance(self.ptr, other.ptr, byref(c_double()))
@property def extent(self): """ Returns the extent of this geometry as a 4-tuple, consisting of (xmin, ymin, xmax, ymax). """ from .point import Point env = self.envelope if isinstance(env, Point): xmin, ymin = env.tuple xmax, ymax = xmin, ymin else: xmin, ymin = env[0][0] xmax, ymax = env[0][2] return (xmin, ymin, xmax, ymax) @property def length(self): """ Returns the length of this Geometry (e.g., 0 for point, or the circumference of a Polygon). """ return capi.geos_length(self.ptr, byref(c_double()))
[docs] def clone(self): "Clones this Geometry." return GEOSGeometry(capi.geom_clone(self.ptr), srid=self.srid)
class LinearGeometryMixin(object): """ Used for LineString and MultiLineString. """ def interpolate(self, distance): return self._topology(capi.geos_interpolate(self.ptr, distance)) def interpolate_normalized(self, distance): return self._topology(capi.geos_interpolate_normalized(self.ptr, distance)) def project(self, point): from .point import Point if not isinstance(point, Point): raise TypeError('locate_point argument must be a Point') return capi.geos_project(self.ptr, point.ptr) def project_normalized(self, point): from .point import Point if not isinstance(point, Point): raise TypeError('locate_point argument must be a Point') return capi.geos_project_normalized(self.ptr, point.ptr) @property def merged(self): """ Return the line merge of this Geometry. """ return self._topology(capi.geos_linemerge(self.ptr)) @property def closed(self): """ Return whether or not this Geometry is closed. """ return capi.geos_isclosed(self.ptr)
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