/usr/lib/python3/dist-packages/shapely/ops.py is in python3-shapely 1.6.4-1.
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"""
import sys
if sys.version_info[0] < 3:
from itertools import izip
else:
izip = zip
from ctypes import byref, c_void_p, c_double
from shapely.geos import lgeos
from shapely.geometry.base import geom_factory, BaseGeometry
from shapely.geometry import asShape, asLineString, asMultiLineString, Point, MultiPoint,\
LineString, MultiLineString, Polygon, GeometryCollection
__all__ = ['cascaded_union', 'linemerge', 'operator', 'polygonize',
'polygonize_full', 'transform', 'unary_union', 'triangulate', 'split']
class CollectionOperator(object):
def shapeup(self, ob):
if isinstance(ob, BaseGeometry):
return ob
else:
try:
return asShape(ob)
except ValueError:
return asLineString(ob)
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
try:
source = iter(source)
except TypeError:
source = [source]
finally:
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._other_owned = False
yield g
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 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 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 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:
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))
operator = CollectionOperator()
polygonize = operator.polygonize
polygonize_full = operator.polygonize_full
linemerge = operator.linemerge
cascaded_union = operator.cascaded_union
unary_union = operator.unary_union
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]
class ValidateOp(object):
def __call__(self, this):
return lgeos.GEOSisValidReason(this._geom)
validate = ValidateOp()
def transform(func, geom):
"""Applies `func` to all coordinates of `geom` and returns a new
geometry of the same type from the transformed coordinates.
`func` maps x, y, and optionally z to output xp, yp, zp. The input
parameters may iterable types like lists or arrays or single values.
The output shall be of the same type. Scalars in, scalars out.
Lists in, lists out.
For example, here is an identity function applicable to both types
of input.
def id_func(x, y, z=None):
return tuple(filter(None, [x, y, z]))
g2 = transform(id_func, g1)
A partially applied transform function from pyproj satisfies the
requirements for `func`.
from functools import partial
import pyproj
project = partial(
pyproj.transform,
pyproj.Proj(init='epsg:4326'),
pyproj.Proj(init='epsg:26913'))
g2 = transform(project, g1)
Lambda expressions such as the one in
g2 = transform(lambda x, y, z=None: (x+1.0, y+1.0), g1)
also satisfy the requirements for `func`.
"""
if geom.is_empty:
return geom
if geom.type in ('Point', 'LineString', 'LinearRing', 'Polygon'):
# First we try to apply func to x, y, z sequences. When func is
# optimized for sequences, this is the fastest, though zipping
# the results up to go back into the geometry constructors adds
# extra cost.
try:
if geom.type in ('Point', 'LineString', 'LinearRing'):
return type(geom)(zip(*func(*izip(*geom.coords))))
elif geom.type == 'Polygon':
shell = type(geom.exterior)(
zip(*func(*izip(*geom.exterior.coords))))
holes = list(type(ring)(zip(*func(*izip(*ring.coords))))
for ring in geom.interiors)
return type(geom)(shell, holes)
# A func that assumes x, y, z are single values will likely raise a
# TypeError, in which case we'll try again.
except TypeError:
if geom.type in ('Point', 'LineString', 'LinearRing'):
return type(geom)([func(*c) for c in geom.coords])
elif geom.type == 'Polygon':
shell = type(geom.exterior)(
[func(*c) for c in geom.exterior.coords])
holes = list(type(ring)([func(*c) for c in ring.coords])
for ring in geom.interiors)
return type(geom)(shell, holes)
elif geom.type.startswith('Multi') or geom.type == 'GeometryCollection':
return type(geom)([transform(func, part) for part in geom.geoms])
else:
raise ValueError('Type %r not recognized' % geom.type)
def nearest_points(g1, g2):
"""Returns the calculated nearest points in the input geometries
The points are returned in the same order as the input geometries.
"""
seq = lgeos.methods['nearest_points'](g1._geom, g2._geom)
if seq is None:
if g1.is_empty:
raise ValueError('The first input geometry is empty')
else:
raise ValueError('The second input geometry is empty')
x1 = c_double()
y1 = c_double()
x2 = c_double()
y2 = c_double()
lgeos.GEOSCoordSeq_getX(seq, 0, byref(x1))
lgeos.GEOSCoordSeq_getY(seq, 0, byref(y1))
lgeos.GEOSCoordSeq_getX(seq, 1, byref(x2))
lgeos.GEOSCoordSeq_getY(seq, 1, byref(y2))
p1 = Point(x1.value, y1.value)
p2 = Point(x2.value, y2.value)
return (p1, p2)
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 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)))
class SplitOp(object):
@staticmethod
def _split_polygon_with_line(poly, splitter):
"""Split a Polygon with a LineString"""
assert(isinstance(poly, Polygon))
assert(isinstance(splitter, LineString))
union = poly.boundary.union(splitter)
# some polygonized geometries may be holes, we do not want them
# that's why we test if the original polygon (poly) contains
# an inner point of polygonized geometry (pg)
return [pg for pg in polygonize(union) if poly.contains(pg.representative_point())]
@staticmethod
def _split_line_with_line(line, splitter):
"""Split a LineString with another (Multi)LineString or (Multi)Polygon"""
# if splitter is a polygon, pick it's boundary
if splitter.type in ('Polygon', 'MultiPolygon'):
splitter = splitter.boundary
assert(isinstance(line, LineString))
assert(isinstance(splitter, LineString) or isinstance(splitter, MultiLineString))
if splitter.crosses(line):
# The lines cross --> return multilinestring from the split
return line.difference(splitter)
elif splitter.relate_pattern(line, '1********'):
# The lines overlap at some segment (linear intersection of interiors)
raise ValueError('Input geometry segment overlaps with the splitter.')
else:
# The lines do not cross --> return collection with identity line
return [line]
@staticmethod
def _split_line_with_point(line, splitter):
"""Split a LineString with a Point"""
assert(isinstance(line, LineString))
assert(isinstance(splitter, Point))
# check if point is in the interior of the line
if not line.relate_pattern(splitter, '0********'):
# point not on line interior --> return collection with single identity line
# (REASONING: Returning a list with the input line reference and creating a
# GeometryCollection at the general split function prevents unnecessary copying
# of linestrings in multipoint splitting function)
return [line]
elif line.coords[0] == splitter.coords[0]:
# if line is a closed ring the previous test doesn't behave as desired
return [line]
# point is on line, get the distance from the first point on line
distance_on_line = line.project(splitter)
coords = list(line.coords)
# split the line at the point and create two new lines
# TODO: can optimize this by accumulating the computed point-to-point distances
for i, p in enumerate(coords):
pd = line.project(Point(p))
if pd == distance_on_line:
return [
LineString(coords[:i+1]),
LineString(coords[i:])
]
elif distance_on_line < pd:
# we must interpolate here because the line might use 3D points
cp = line.interpolate(distance_on_line)
ls1_coords = coords[:i]
ls1_coords.append(cp.coords[0])
ls2_coords = [cp.coords[0]]
ls2_coords.extend(coords[i:])
return [LineString(ls1_coords), LineString(ls2_coords)]
@staticmethod
def _split_line_with_multipoint(line, splitter):
"""Split a LineString with a MultiPoint"""
assert(isinstance(line, LineString))
assert(isinstance(splitter, MultiPoint))
chunks = [line]
for pt in splitter.geoms:
new_chunks = []
for chunk in filter(lambda x: not x.is_empty, chunks):
# add the newly split 2 lines or the same line if not split
new_chunks.extend(SplitOp._split_line_with_point(chunk, pt))
chunks = new_chunks
return chunks
@staticmethod
def split(geom, splitter):
"""
Splits a geometry by another geometry and returns a collection of geometries. This function is the theoretical
opposite of the union of the split geometry parts. If the splitter does not split the geometry, a collection
with a single geometry equal to the input geometry is returned.
The function supports:
- Splitting a (Multi)LineString by a (Multi)Point or (Multi)LineString or (Multi)Polygon
- Splitting a (Multi)Polygon by a LineString
It may be convenient to snap the splitter with low tolerance to the geometry. For example in the case
of splitting a line by a point, the point must be exactly on the line, for the line to be correctly split.
When splitting a line by a polygon, the boundary of the polygon is used for the operation.
When splitting a line by another line, a ValueError is raised if the two overlap at some segment.
Parameters
----------
geom : geometry
The geometry to be split
splitter : geometry
The geometry that will split the input geom
Example
-------
>>> pt = Point((1, 1))
>>> line = LineString([(0,0), (2,2)])
>>> result = split(line, pt)
>>> result.wkt
'GEOMETRYCOLLECTION (LINESTRING (0 0, 1 1), LINESTRING (1 1, 2 2))'
"""
if geom.type in ('MultiLineString', 'MultiPolygon'):
return GeometryCollection([i for part in geom.geoms for i in SplitOp.split(part, splitter).geoms])
elif geom.type == 'LineString':
if splitter.type in ('LineString', 'MultiLineString', 'Polygon', 'MultiPolygon'):
split_func = SplitOp._split_line_with_line
elif splitter.type in ('Point'):
split_func = SplitOp._split_line_with_point
elif splitter.type in ('MultiPoint'):
split_func = SplitOp._split_line_with_multipoint
else:
raise ValueError("Splitting a LineString with a %s is not supported" % splitter.type)
elif geom.type == 'Polygon':
if splitter.type == 'LineString':
split_func = SplitOp._split_polygon_with_line
else:
raise ValueError("Splitting a Polygon with a %s is not supported" % splitter.type)
else:
raise ValueError("Splitting %s geometry is not supported" % geom.type)
return GeometryCollection(split_func(geom, splitter))
split = SplitOp.split
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