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 (srid is None) or (srid < 0):
warnings.warn(
"Calling transform() with no SRID set does no transformation!",
stacklevel=2)
warnings.warn(
"Calling transform() with no SRID will raise GEOSException in v1.5",
FutureWarning,
stacklevel=2)
return
if not gdal.HAS_GDAL:
raise GEOSException(
"GDAL library is not available to transform() geometry.")
# 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.')
def check_geom(result, func, cargs):
"Error checking on routines that return Geometries."
if not result:
raise GEOSException(
'Error encountered checking Geometry returned from GEOS C function "%s".'
% func.__name__)
return result
def cascaded_union(self):
"Returns a cascaded union of this MultiPolygon."
if GEOS_PREPARE:
return GEOSGeometry(capi.geos_cascaded_union(self.ptr), self.srid)
else:
raise GEOSException(
'The cascaded union operation requires GEOS 3.1+.')
def valid_reason(self):
"""
Returns a string containing the reason for any invalidity.
"""
if not GEOS_PREPARE:
raise GEOSException('Upgrade GEOS to 3.1 to get validity reason.')
return capi.geos_isvalidreason(self.ptr)
def check_minus_one(result, func, cargs):
"Error checking on routines that should not return -1."
if result == -1:
raise GEOSException('Error encountered in GEOS C function "%s".' %
func.__name__)
else:
return result
def _get_ptr(self):
# Raise an exception if the pointer isn't valid don't
# want to be passing NULL pointers to routines --
# that's very bad.
if self._ptr: return self._ptr
else:
raise GEOSException('NULL GEOS %s pointer encountered.' %
self.__class__.__name__)
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, basestring) or len(pattern) > 9:
raise GEOSException('invalid intersection matrix pattern')
return capi.geos_relatepattern(self.ptr, other.ptr, pattern)
def __setstate__(self, state):
# Instantiating from the tuple state that was pickled.
wkb, srid = state
ptr = wkb_r().read(buffer(wkb))
if not ptr:
raise GEOSException('Invalid Geometry loaded from pickled state.')
self.ptr = ptr
self._post_init(srid)
def ogr(self):
"Returns the OGR Geometry for this Geometry."
if gdal.HAS_GDAL:
if self.srid:
return gdal.OGRGeometry(self.wkb, self.srid)
else:
return gdal.OGRGeometry(self.wkb)
else:
raise GEOSException('GDAL required to convert to an OGRGeometry.')
def json(self):
"""
Returns GeoJSON representation of this Geometry if GDAL 1.5+
is installed.
"""
if gdal.GEOJSON:
return self.ogr.json
else:
raise GEOSException('GeoJSON output only supported on GDAL 1.5+.')
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, basestring):
if isinstance(geo_input, unicode):
# Encoding to ASCII, WKT or HEXEWKB doesn't need any more.
geo_input = geo_input.encode('ascii')
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(wkt_m.group('wkt'))
elif hex_regex.match(geo_input):
# Handling HEXEWKB input.
g = wkb_r().read(geo_input)
elif gdal.GEOJSON and json_regex.match(geo_input):
# Handling GeoJSON input.
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 geomtry (GEOM_PTR).
g = geo_input
elif isinstance(geo_input, buffer):
# 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 bool(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 check_predicate(result, func, cargs):
"Error checking for unary/binary predicate functions."
val = ord(result) # getting the ordinal from the character
if val == 1: return True
elif val == 0: return False
else:
raise GEOSException(
'Error encountered on GEOS C predicate function "%s".' %
func.__name__)
def prepared(self):
"""
Returns a PreparedGeometry corresponding to this geometry -- it is
optimized for the contains, intersects, and covers operations.
"""
if GEOS_PREPARE:
return PreparedGeometry(self)
else:
raise GEOSException(
'GEOS 3.1+ required for prepared geometry support.')
def srs(self):
"Returns the OSR SpatialReference for SRID of this Geometry."
if gdal.HAS_GDAL:
if self.srid:
return gdal.SpatialReference(self.srid)
else:
return None
else:
raise GEOSException(
'GDAL required to return a SpatialReference object.')
def _set_list(self, length, items):
ptr = self._create_point(length, items)
if ptr:
capi.destroy_geom(self.ptr)
self._ptr = ptr
self._set_cs()
else:
# can this happen?
raise GEOSException(
'Geometry resulting from slice deletion was invalid.')
def geos_version_info():
"""
Returns a dictionary containing the various version metadata parsed from
the GEOS version string, including the version number, whether the version
is a release candidate (and what number release candidate), and the C API
version.
"""
ver = geos_version()
m = version_regex.match(ver)
if not m:
raise GEOSException('Could not parse version info string "%s"' % ver)
return dict((key, m.group(key))
for key in ('version', 'release_candidate', 'capi_version',
'major', 'minor', 'subminor'))
def hexewkb(self):
"""
Returns the EWKB of this Geometry in hexadecimal form. This is an
extension of the WKB specification that includes SRID and Z values
that are a part of this geometry.
"""
if self.hasz:
if not GEOS_PREPARE:
# See: http://trac.osgeo.org/geos/ticket/216
raise GEOSException(
'Upgrade GEOS to 3.1 to get valid 3D HEXEWKB.')
return ewkb_w3d().write_hex(self)
else:
return ewkb_w().write_hex(self)
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
and Z values that are a part of this geometry.
"""
if self.hasz:
if not GEOS_PREPARE:
# See: http://trac.osgeo.org/geos/ticket/216
raise GEOSException(
'Upgrade GEOS to 3.1 to get valid 3D EWKB.')
return ewkb_w3d().write(self)
else:
return ewkb_w().write(self)
def check_string(result, func, cargs):
"""
Error checking for routines that return strings.
This frees the memory allocated by GEOS at the result pointer.
"""
if not result:
raise GEOSException(
'Error encountered checking string return value in GEOS C function "%s".'
% func.__name__)
# Getting the string value at the pointer address.
s = string_at(result)
# Freeing the memory allocated within GEOS
free(result)
return s
def check_sized_string(result, func, cargs):
"""
Error checking for routines that return explicitly sized strings.
This frees the memory allocated by GEOS at the result pointer.
"""
if not result:
raise GEOSException(
'Invalid string pointer returned by GEOS C function "%s"' %
func.__name__)
# A c_size_t object is passed in by reference for the second
# argument on these routines, and its needed to determine the
# correct size.
s = string_at(result, last_arg_byref(cargs))
# Freeing the memory allocated within GEOS
free(result)
return s
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.')
def _checkdim(self, dim):
"Checks the given dimension."
if dim < 0 or dim > 2:
raise GEOSException('invalid ordinate dimension "%d"' % dim)
def set_z(self, value):
"Sets the Z component of the Point."
if self.hasz:
self._cs.setOrdinate(2, 0, value)
else:
raise GEOSException('Cannot set Z on 2D Point.')