def polygonize_full(self, lines):
"""Creates polygons from a source of lines, returning the polygons
and leftover geometries.
The source may be a MultiLineString, a sequence of LineString objects,
or a sequence of objects than can be adapted to LineStrings.
Returns a tuple of objects: (polygons, dangles, cut edges, invalid ring
lines). Each are a geometry collection.
Dangles are edges which have one or both ends which are not incident on
another edge endpoint. Cut edges are connected at both ends but do not
form part of polygon. Invalid ring lines form rings which are invalid
(bowties, etc).
"""
source = getattr(lines, "geoms", None) or lines
try:
source = iter(source)
except TypeError:
source = [source]
finally:
obs = [self.shapeup(l) for l in source]
L = len(obs)
subs = (c_void_p * L)()
for i, g in enumerate(obs):
subs[i] = g._geom
collection = lgeos.GEOSGeom_createCollection(5, subs, L)
dangles = c_void_p()
cuts = c_void_p()
invalids = c_void_p()
product = lgeos.GEOSPolygonize_full(collection, byref(dangles), byref(cuts), byref(invalids))
return (geom_factory(product), geom_factory(dangles), geom_factory(cuts), geom_factory(invalids))
def polygonize_full(self, lines):
"""Creates polygons from a source of lines, returning the polygons
and leftover geometries.
The source may be a MultiLineString, a sequence of LineString objects,
or a sequence of objects than can be adapted to LineStrings.
Returns a tuple of objects: (polygons, dangles, cut edges, invalid ring
lines). Each are a geometry collection.
Dangles are edges which have one or both ends which are not incident on
another edge endpoint. Cut edges are connected at both ends but do not
form part of polygon. Invalid ring lines form rings which are invalid
(bowties, etc).
"""
source = getattr(lines, 'geoms', None) or lines
try:
source = iter(source)
except TypeError:
source = [source]
finally:
obs = [self.shapeup(l) for l in source]
L = len(obs)
subs = (c_void_p * L)()
for i, g in enumerate(obs):
subs[i] = g._geom
collection = lgeos.GEOSGeom_createCollection(5, subs, L)
dangles = c_void_p()
cuts = c_void_p()
invalids = c_void_p()
product = lgeos.GEOSPolygonize_full(collection, byref(dangles),
byref(cuts), byref(invalids))
return (geom_factory(product), geom_factory(dangles),
geom_factory(cuts), geom_factory(invalids))
def polygonize(iterator):
"""Creates polygons from a list of LineString objects.
"""
lines = [shapeup(ob) for ob in iterator]
geom_array_type = c_void_p * len(lines)
geom_array = geom_array_type()
for i, line in enumerate(lines):
geom_array[i] = line._geom
product = lgeos.GEOSPolygonize(byref(geom_array), len(lines))
collection = geom_factory(product)
for g in collection.geoms:
clone = lgeos.GEOSGeom_clone(g._geom)
g = geom_factory(clone)
g._owned = False
yield g
def parallel_offset(self,
distance,
side,
resolution=16,
join_style=JOIN_STYLE.round,
mitre_limit=1.0):
"""Returns a LineString or MultiLineString geometry at a distance from
the object on its right or its left side.
Distance must be a positive float value. The side parameter may be
'left' or 'right'. The resolution of the buffer around each vertex of
the object increases by increasing the resolution keyword parameter or
third positional parameter.
The join style is for outside corners between line segments. Accepted
values are JOIN_STYLE.round (1), JOIN_STYLE.mitre (2), and
JOIN_STYLE.bevel (3).
The mitre ratio limit is used for very sharp corners. It is the ratio
of the distance from the corner to the end of the mitred offset corner.
When two line segments meet at a sharp angle, a miter join will extend
far beyond the original geometry. To prevent unreasonable geometry, the
mitre limit allows controlling the maximum length of the join corner.
Corners with a ratio which exceed the limit will be beveled."""
try:
return geom_factory(self.impl['parallel_offset'](
self, distance, resolution, join_style, mitre_limit,
bool(side == 'left')))
except OSError:
raise TopologicalError()
def make_valid(ob):
"""
Make the input geometry valid according to the GEOS MakeValid algorithm.
If the input geometry is already valid, then it will be returned.
If the geometry must be split into multiple parts of the same type to be made valid,
then a multi-part geometry will be returned.
If the geometry must be split into multiple parts of different types to be made valid,
then a GeometryCollection will be returned.
Parameters
----------
ob : Geometry
A shapely geometry object which should be made valid. If the object is already valid,
it will be returned as-is.
Returns
-------
Geometry
The input geometry, made valid according to the GEOS MakeValid algorithm.
"""
if ob.is_valid:
return ob
return geom_factory(lgeos.GEOSMakeValid(ob._geom))
def snap(g1, g2, tolerance):
"""Snap one geometry to another with a given tolerance
Vertices of the first geometry are snapped to vertices of the second
geometry. The resulting snapped geometry is returned. The input geometries
are not modified.
Parameters
----------
g1 : geometry
The first geometry
g2 : geometry
The second geometry
tolerence : float
The snapping tolerance
Example
-------
>>> square = Polygon([(1,1), (2, 1), (2, 2), (1, 2), (1, 1)])
>>> line = LineString([(0,0), (0.8, 0.8), (1.8, 0.95), (2.6, 0.5)])
>>> result = snap(line, square, 0.5)
>>> result.wkt
'LINESTRING (0 0, 1 1, 2 1, 2.6 0.5)'
"""
return (geom_factory(lgeos.methods['snap'](g1._geom, g2._geom, tolerance)))
def clip_by_rect(geom, xmin, ymin, xmax, ymax):
"""Returns the portion of a geometry within a rectangle
The geometry is clipped in a fast but possibly dirty way. The output is
not guaranteed to be valid. No exceptions will be raised for topological
errors.
Parameters
----------
geom : geometry
The geometry to be clipped
xmin : float
Minimum x value of the rectangle
ymin : float
Minimum y value of the rectangle
xmax : float
Maximum x value of the rectangle
ymax : float
Maximum y value of the rectangle
Notes
-----
Requires GEOS >= 3.5.0
New in 1.7.
"""
if geom.is_empty:
return geom
result = geom_factory(lgeos.methods['clip_by_rect'](geom._geom, xmin, ymin, xmax, ymax))
return result
def clip_by_rect(geom, xmin, ymin, xmax, ymax):
"""Returns the portion of a geometry within a rectangle
The geometry is clipped in a fast but possibly dirty way. The output is
not guaranteed to be valid. No exceptions will be raised for topological
errors.
Parameters
----------
geom : geometry
The geometry to be clipped
xmin : float
Minimum x value of the rectangle
ymin : float
Minimum y value of the rectangle
xmax : float
Maximum x value of the rectangle
ymax : float
Maximum y value of the rectangle
Notes
-----
Requires GEOS >= 3.5.0
New in 1.7.
"""
if geom.is_empty:
return geom
result = geom_factory(lgeos.methods['clip_by_rect'](geom._geom, xmin, ymin,
xmax, ymax))
return result
def loads(data):
"""Load a geometry from a WKT string."""
from shapely.geometry.base import geom_factory
geom = lgeos.GEOSGeomFromWKT(c_char_p(data.encode('utf-8')))
if not geom:
raise ReadingError("Could not create geometry because of errors while reading input.")
return geom_factory(geom)
def dumps(ob, hex=False, srid=None, **kw):
"""Dump a WKB representation of a geometry to a byte string, or a
hex-encoded string if ``hex=True``.
Parameters
----------
ob : geometry
The geometry to export to well-known binary (WKB) representation
hex : bool
If true, export the WKB as a hexidecimal string. The default is to
return a binary string/bytes object.
srid : int
Spatial reference system ID to include in the output. The default value
means no SRID is included.
**kw : kwargs
See available keyword output settings in ``shapely.geos.WKBWriter``."""
if srid is not None:
# clone the object and set the SRID before dumping
geom = lgeos.GEOSGeom_clone(ob._geom)
lgeos.GEOSSetSRID(geom, srid)
ob = geom_factory(geom)
kw["include_srid"] = True
writer = WKBWriter(lgeos, **kw)
if hex:
return writer.write_hex(ob)
else:
return writer.write(ob)
def parallel_offset(self, distance, side, resolution=16, join_style=1, mitre_limit=1.0):
"""Returns a LineString or MultiLineString geometry at a distance from
the object on its right or its left side.
Distance must be a positive float value. The side parameter may be
'left' or 'right'. The resolution of the buffer around each vertex of
the object increases by increasing the resolution keyword parameter or
third positional parameter.
The join style is for outside corners between line segments. Accepted
values are 1 => ROUND, 2 => MITRE, 3 => BEVEL.
The mitre ratio limit is used for very sharp corners. It is the ratio
of the distance from the corner to the end of the mitred offset corner.
When two line segments meet at a sharp angle, a miter join will extend
far beyond the original geometry. To prevent unreasonable geometry, the
mitre limit allows controlling the maximum length of the join corner.
Corners with a ratio which exceed the limit will be beveled."""
try:
return geom_factory(
self.impl["parallel_offset"](self, distance, resolution, join_style, mitre_limit, bool(side == "left"))
)
except WindowsError:
raise TopologicalError()
def snap(g1, g2, tolerance):
"""Snap one geometry to another with a given tolerance
Vertices of the first geometry are snapped to vertices of the second
geometry. The resulting snapped geometry is returned. The input geometries
are not modified.
Parameters
----------
g1 : geometry
The first geometry
g2 : geometry
The second geometry
tolerence : float
The snapping tolerance
Example
-------
>>> square = Polygon([(1,1), (2, 1), (2, 2), (1, 2), (1, 1)])
>>> line = LineString([(0,0), (0.8, 0.8), (1.8, 0.95), (2.6, 0.5)])
>>> result = snap(line, square, 0.5)
>>> result.wkt
'LINESTRING (0 0, 1 1, 2 1, 2.6 0.5)'
"""
return(geom_factory(lgeos.methods['snap'](g1._geom, g2._geom, tolerance)))
def parallel_offset(
self, distance, side='right',
resolution=16, join_style=JOIN_STYLE.round, mitre_limit=5.0):
"""Returns a LineString or MultiLineString geometry at a distance from
the object on its right or its left side.
The side parameter may be 'left' or 'right' (default is 'right'). The
resolution of the buffer around each vertex of the object increases by
increasing the resolution keyword parameter or third positional
parameter. If the distance parameter is negative the side is inverted,
e.g. distance=5.0, side='left' is the same as distance=-5.0,
side='right'.
The join style is for outside corners between line segments. Accepted
values are JOIN_STYLE.round (1), JOIN_STYLE.mitre (2), and
JOIN_STYLE.bevel (3).
The mitre ratio limit is used for very sharp corners. It is the ratio
of the distance from the corner to the end of the mitred offset corner.
When two line segments meet at a sharp angle, a miter join will extend
far beyond the original geometry. To prevent unreasonable geometry, the
mitre limit allows controlling the maximum length of the join corner.
Corners with a ratio which exceed the limit will be beveled."""
if mitre_limit == 0.0:
raise ValueError(
'Cannot compute offset from zero-length line segment')
try:
return geom_factory(self.impl['parallel_offset'](
self, distance, resolution, join_style, mitre_limit, side))
except OSError:
raise TopologicalError()
def dumps(ob, hex=False, srid=None, **kw):
"""Dump a WKB representation of a geometry to a byte string, or a
hex-encoded string if ``hex=True``.
Parameters
----------
ob : geometry
The geometry to export to well-known binary (WKB) representation
hex : bool
If true, export the WKB as a hexidecimal string. The default is to
return a binary string/bytes object.
srid : int
Spatial reference system ID to include in the output. The default value
means no SRID is included.
**kw : kwargs
See available keyword output settings in ``shapely.geos.WKBWriter``."""
if srid is not None:
# clone the object and set the SRID before dumping
geom = lgeos.GEOSGeom_clone(ob._geom)
lgeos.GEOSSetSRID(geom, srid)
ob = geom_factory(geom)
kw["include_srid"] = True
writer = WKBWriter(lgeos, **kw)
if hex:
return writer.write_hex(ob)
else:
return writer.write(ob)
def loads(data):
"""Load a geometry from a WKT string."""
geom = lgeos.GEOSGeomFromWKT(c_char_p(data))
if not geom:
raise ReadingError, \
"Could not create geometry because of errors while reading input."
return geom_factory(geom)
def loads(data):
"""Load a geometry from a WKT string."""
from shapely.geometry.base import geom_factory
geom = lgeos.GEOSGeomFromWKT(c_char_p(data))
if not geom:
raise ReadingError, \
"Could not create geometry because of errors while reading input."
return geom_factory(geom)
def linemerge(shape):
""" Returns a geometry with lines merged using GEOSLineMerge.
"""
if shape.type != 'MultiLineString':
return shape
# copied from shapely.ops.linemerge at http://github.com/sgillies/shapely
result = lgeos.GEOSLineMerge(shape._geom)
return geom_factory(result)
def linemerge(shape):
""" Returns a geometry with lines merged using GEOSLineMerge.
"""
if shape.type != 'MultiLineString':
return shape
# copied from shapely.ops.linemerge at http://github.com/sgillies/shapely
result = lgeos.GEOSLineMerge(shape._geom)
return geom_factory(result)
def voronoi_diagram(geom, envelope=None, tolerance=0.0, edges=False):
"""
Constructs a Voronoi Diagram [1] from the given geometry.
Returns a list of geometries.
Parameters
----------
geom: geometry
the input geometry whose vertices will be used to calculate
the final diagram.
envelope: geometry, None
clipping envelope for the returned diagram, automatically
determined if None. The diagram will be clipped to the larger
of this envelope or an envelope surrounding the sites.
tolerance: float, 0.0
sets the snapping tolerance used to improve the robustness
of the computation. A tolerance of 0.0 specifies that no
snapping will take place.
edges: bool, False
If False, return regions as polygons. Else, return only
edges e.g. LineStrings.
GEOS documentation can be found at [2]
Returns
-------
GeometryCollection
geometries representing the Voronoi regions.
Notes
-----
The tolerance `argument` can be finicky and is known to cause the
algorithm to fail in several cases. If you're using `tolerance`
and getting a failure, try removing it. The test cases in
tests/test_voronoi_diagram.py show more details.
References
----------
[1] https://en.wikipedia.org/wiki/Voronoi_diagram
[2] https://geos.osgeo.org/doxygen/geos__c_8h_source.html (line 730)
"""
func = lgeos.methods['voronoi_diagram']
envelope = envelope._geom if envelope else None
try:
result = geom_factory(func(geom._geom, envelope, tolerance,
int(edges)))
except ValueError:
errstr = "Could not create Voronoi Diagram with the specified inputs."
if tolerance:
errstr += " Try running again with default tolerance value."
raise ValueError(errstr)
if result.type != 'GeometryCollection':
return GeometryCollection([result])
return result
def polygonize(self, lines):
"""Creates polygons from a source of lines
The source may be a MultiLineString, a sequence of LineString objects,
or a sequence of objects than can be adapted to LineStrings.
"""
source = getattr(lines, 'geoms', None) or lines
obs = [self.shapeup(l) for l in source]
geom_array_type = c_void_p * len(obs)
geom_array = geom_array_type()
for i, line in enumerate(obs):
geom_array[i] = line._geom
product = lgeos.GEOSPolygonize(byref(geom_array), len(obs))
collection = geom_factory(product)
for g in collection.geoms:
clone = lgeos.GEOSGeom_clone(g._geom)
g = geom_factory(clone)
g._owned = False
yield g
def polygonize(self, lines):
"""Creates polygons from a source of lines
The source may be a MultiLineString, a sequence of LineString objects,
or a sequence of objects than can be adapted to LineStrings.
"""
source = getattr(lines, 'geoms', None) or lines
obs = [self.shapeup(l) for l in source]
geom_array_type = c_void_p * len(obs)
geom_array = geom_array_type()
for i, line in enumerate(obs):
geom_array[i] = line._geom
product = lgeos.GEOSPolygonize(byref(geom_array), len(obs))
collection = geom_factory(product)
for g in collection.geoms:
clone = lgeos.GEOSGeom_clone(g._geom)
g = geom_factory(clone)
g._owned = False
yield g
def unary_union(self, geoms):
"""Returns the union of a sequence of geometries
This is the most efficient method of dissolving many polygons.
"""
L = len(geoms)
subs = (c_void_p * L)()
for i, g in enumerate(geoms):
subs[i] = g._geom
collection = lgeos.GEOSGeom_createCollection(6, subs, L)
return geom_factory(lgeos.GEOSUnaryUnion(collection))
def read(self, text):
"""Returns geometry from WKT"""
if sys.version_info[0] >= 3:
text = text.encode('ascii')
geom = self._lgeos.GEOSWKTReader_read(self._reader, c_char_p(text))
if not geom:
raise ReadingError("Could not create geometry because of errors "
"while reading input.")
# avoid circular import dependency
from shapely.geometry.base import geom_factory
return geom_factory(geom)
def read(self, text):
"""Returns geometry from WKT"""
if sys.version_info[0] >= 3:
text = text.encode('ascii')
geom = self._lgeos.GEOSWKTReader_read(self._reader, c_char_p(text))
if not geom:
raise ReadingError("Could not create geometry because of errors "
"while reading input.")
# avoid circular import dependency
from shapely.geometry.base import geom_factory
return geom_factory(geom)
def cascaded_union(self, geoms):
"""Returns the union of a sequence of geometries
This is the most efficient method of dissolving many polygons.
"""
L = len(geoms)
subs = (c_void_p * L)()
for i, g in enumerate(geoms):
subs[i] = g._geom
collection = lgeos.GEOSGeom_createCollection(6, subs, L)
return geom_factory(lgeos.methods['cascaded_union'](collection))
def unary_union(self, geoms):
"""Returns the union of a sequence of geometries
This method replaces :meth:`cascaded_union` as the
prefered method for dissolving many polygons.
"""
L = len(geoms)
subs = (c_void_p * L)()
for i, g in enumerate(geoms):
subs[i] = g._geom
collection = lgeos.GEOSGeom_createCollection(6, subs, L)
return geom_factory(lgeos.methods['unary_union'](collection))
def unary_union(self, geoms):
"""Returns the union of a sequence of geometries
This method replaces :meth:`cascaded_union` as the
prefered method for dissolving many polygons.
"""
L = len(geoms)
subs = (c_void_p * L)()
for i, g in enumerate(geoms):
subs[i] = g._geom
collection = lgeos.GEOSGeom_createCollection(6, subs, L)
return geom_factory(lgeos.methods['unary_union'](collection))
def read(self, text):
"""Returns geometry from WKT"""
if not isinstance(text, str):
raise TypeError("Only str is accepted.")
text = text.encode()
c_string = c_char_p(text)
geom = self._lgeos.GEOSWKTReader_read(self._reader, c_string)
if not geom:
raise WKTReadingError(
"Could not create geometry because of errors "
"while reading input.")
# avoid circular import dependency
from shapely.geometry.base import geom_factory
return geom_factory(geom)
def _shapely_normalize(geom):
"""
Small helper function for now because it is not yet available in Shapely.
"""
from shapely.geos import lgeos
from shapely.geometry.base import geom_factory
from ctypes import c_void_p, c_int
lgeos._lgeos.GEOSNormalize_r.restype = c_int
lgeos._lgeos.GEOSNormalize_r.argtypes = [c_void_p, c_void_p]
geom_cloned = lgeos.GEOSGeom_clone(geom._geom)
lgeos._lgeos.GEOSNormalize_r(lgeos.geos_handle, geom_cloned)
return geom_factory(geom_cloned)
def cascaded_union(self, geoms):
"""Returns the union of a sequence of geometries
This method was superseded by :meth:`unary_union`.
"""
try:
L = len(geoms)
except TypeError:
geoms = [geoms]
L = 1
subs = (c_void_p * L)()
for i, g in enumerate(geoms):
subs[i] = g._geom
collection = lgeos.GEOSGeom_createCollection(6, subs, L)
return geom_factory(lgeos.methods['cascaded_union'](collection))
def cascaded_union(self, geoms):
"""Returns the union of a sequence of geometries
This is the most efficient method of dissolving many polygons.
"""
try:
L = len(geoms)
except TypeError:
geoms = [geoms]
L = 1
subs = (c_void_p * L)()
for i, g in enumerate(geoms):
subs[i] = g._geom
collection = lgeos.GEOSGeom_createCollection(6, subs, L)
return geom_factory(lgeos.methods["cascaded_union"](collection))
def read(self, text):
"""Returns geometry from WKT"""
if not isinstance(text, text_types):
raise TypeError("Only str is accepted.")
if sys.version_info[0] >= 3:
text = text.encode()
c_string = c_char_p(text)
geom = self._lgeos.GEOSWKTReader_read(self._reader, c_string)
if not geom:
raise WKTReadingError(
"Could not create geometry because of errors "
"while reading input.")
# avoid circular import dependency
from shapely.geometry.base import geom_factory
return geom_factory(geom)
def triangulate(geom, tolerance=0.0, edges=False):
"""Creates the Delaunay triangulation and returns a list of geometries
The source may be any geometry type. All vertices of the geometry will be
used as the points of the triangulation.
From the GEOS documentation:
tolerance is the snapping tolerance used to improve the robustness of
the triangulation computation. A tolerance of 0.0 specifies that no
snapping will take place.
If edges is False, a list of Polygons (triangles) will be returned.
Otherwise the list of LineString edges is returned.
"""
func = lgeos.methods["delaunay_triangulation"]
gc = geom_factory(func(geom._geom, tolerance, int(edges)))
return [g for g in gc.geoms]
def unary_union(self, geoms):
"""Returns the union of a sequence of geometries
This method replaces :meth:`cascaded_union` as the
prefered method for dissolving many polygons.
"""
try:
if isinstance(geoms, BaseMultipartGeometry):
geoms = geoms.geoms
L = len(geoms)
except TypeError:
geoms = [geoms]
L = 1
subs = (c_void_p * L)()
for i, g in enumerate(geoms):
subs[i] = g._geom
collection = lgeos.GEOSGeom_createCollection(6, subs, L)
return geom_factory(lgeos.methods['unary_union'](collection))
def triangulate(geom, tolerance=0.0, edges=False):
"""Creates the Delaunay triangulation and returns a list of geometries
The source may be any geometry type. All vertices of the geometry will be
used as the points of the triangulation.
From the GEOS documentation:
tolerance is the snapping tolerance used to improve the robustness of
the triangulation computation. A tolerance of 0.0 specifies that no
snapping will take place.
If edges is False, a list of Polygons (triangles) will be returned.
Otherwise the list of LineString edges is returned.
"""
func = lgeos.methods['delaunay_triangulation']
gc = geom_factory(func(geom._geom, tolerance, int(edges)))
return [g for g in gc.geoms]
def linemerge(self, lines):
"""Merges all connected lines from a source
The source may be a MultiLineString, a sequence of LineString objects,
or a sequence of objects than can be adapted to LineStrings. Returns a
LineString or MultiLineString when lines are not contiguous.
"""
source = None
if hasattr(lines, 'type') and lines.type == 'MultiLineString':
source = lines
elif hasattr(lines, '__iter__'):
try:
source = asMultiLineString([ls.coords for ls in lines])
except AttributeError:
source = asMultiLineString(lines)
if source is None:
raise ValueError("Cannot linemerge %s" % lines)
result = lgeos.GEOSLineMerge(source._geom)
return geom_factory(result)
def linemerge(self, lines):
"""Merges all connected lines from a source
The source may be a MultiLineString, a sequence of LineString objects,
or a sequence of objects than can be adapted to LineStrings. Returns a
LineString or MultiLineString when lines are not contiguous.
"""
source = None
if hasattr(lines, "type") and lines.type == "MultiLineString":
source = lines
elif hasattr(lines, "__iter__"):
try:
source = asMultiLineString([ls.coords for ls in lines])
except AttributeError:
source = asMultiLineString(lines)
if source is None:
raise ValueError("Cannot linemerge %s" % lines)
result = lgeos.GEOSLineMerge(source._geom)
return geom_factory(result)
def shared_paths(g1, g2):
"""Find paths shared between the two given lineal geometries
Returns a GeometryCollection with two elements:
- First element is a MultiLineString containing shared paths with the
same direction for both inputs.
- Second element is a MultiLineString containing shared paths with the
opposite direction for the two inputs.
Parameters
----------
g1 : geometry
The first geometry
g2 : geometry
The second geometry
"""
if not isinstance(g1, LineString):
raise TypeError("First geometry must be a LineString")
if not isinstance(g2, LineString):
raise TypeError("Second geometry must be a LineString")
return (geom_factory(lgeos.methods['shared_paths'](g1._geom, g2._geom)))
def single_sided_buffer(self, distance, leftSide, resolution=16, joinStyle=1, mitreLimit=1.0):
"""Returns a LineString or MultiLineString geometry at a distance from the object
on its right or its left side.
Distance must be positive. The side is given by the leftSide parameter.
True => LEFT, False => RIGHT
The resolution of the buffer around each vertex of the object increases
by increasing the resolution keyword parameter or third positional parameter.
The join style is for outside corners between line segments.
Values are 1 => ROUND, 2 => MITRE, 3 => BEVEL.
The mitre ratio limit is used for very sharp corners.
It is the ratio of the distance from the corner to the end of the mitred offset
corner. When two line segments meet at a sharp angle, a miter join will extend
far beyond the original geometry. To prevent unreasonable geometry, the mitre
limit allows controlling the maximum length of the join corner.
Corners with a ratio which exceed the limit will be beveled.
"""
try:
return geom_factory(self.impl['single_sided_buffer'](self, distance, resolution, joinStyle, mitreLimit, leftSide))
except WindowsError:
raise TopologicalError()
def shared_paths(g1, g2):
"""Find paths shared between the two given lineal geometries
Returns a GeometryCollection with two elements:
- First element is a MultiLineString containing shared paths with the
same direction for both inputs.
- Second element is a MultiLineString containing shared paths with the
opposite direction for the two inputs.
Parameters
----------
g1 : geometry
The first geometry
g2 : geometry
The second geometry
"""
if not isinstance(g1, LineString):
raise TypeError("First geometry must be a LineString")
if not isinstance(g2, LineString):
raise TypeError("Second geometry must be a LineString")
return(geom_factory(lgeos.methods['shared_paths'](g1._geom, g2._geom)))
def cascaded_union(self, geoms):
"""Returns the union of a sequence of geometries
This function is deprecated, as it was superseded by
:meth:`unary_union`.
"""
warn(
"The 'cascaded_union()' function is deprecated. "
"Use 'unary_union()' instead.",
ShapelyDeprecationWarning, stacklevel=2)
try:
if isinstance(geoms, BaseMultipartGeometry):
geoms = geoms.geoms
L = len(geoms)
except TypeError:
geoms = [geoms]
L = 1
subs = (c_void_p * L)()
for i, g in enumerate(geoms):
subs[i] = g._geom
collection = lgeos.GEOSGeom_createCollection(6, subs, L)
return geom_factory(lgeos.methods['cascaded_union'](collection))
def loads(data):
"""Load a geometry from a WKB string."""
from shapely.geometry.base import geom_factory
return geom_factory(deserialize(data))
def loads(data):
"""Load a geometry from a WKB string."""
from shapely.geometry.base import geom_factory
return geom_factory(deserialize(data))