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
if not isinstance(line, LineString):
raise GeometryTypeError("First argument must be a LineString")
if not isinstance(splitter, LineString) and not isinstance(
splitter, MultiLineString):
raise GeometryTypeError(
"Second argument must be either a LineString or a MultiLineString"
)
# | s\l | Interior | Boundary | Exterior |
# |----------|----------|----------|----------|
# | Interior | 0 or F | * | * | At least one of these two must be 0
# | Boundary | 0 or F | * | * | So either '0********' or '[0F]**0*****'
# | Exterior | * | * | * | No overlapping interiors ('1********')
relation = splitter.relate(line)
if relation[0] == "1":
# The lines overlap at some segment (linear intersection of interiors)
raise ValueError(
"Input geometry segment overlaps with the splitter.")
elif relation[0] == "0" or relation[3] == "0":
# The splitter crosses or touches the line's interior --> return multilinestring from the split
return line.difference(splitter)
else:
# The splitter does not cross or touch the line's interior --> return collection with identity line
return [line]
def _split_line_with_multipoint(line, splitter):
"""Split a LineString with a MultiPoint"""
if not isinstance(line, LineString):
raise GeometryTypeError("First argument must be a LineString")
if not isinstance(splitter, MultiPoint):
raise GeometryTypeError("Second argument must be a 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
def shape(context):
"""
Returns a new, independent geometry with coordinates *copied* from the
context. Changes to the original context will not be reflected in the
geometry object.
Parameters
----------
context :
a GeoJSON-like dict, which provides a "type" member describing the type
of the geometry and "coordinates" member providing a list of coordinates,
or an object which implements __geo_interface__.
Returns
-------
Geometry object
Examples
--------
Create a Point from GeoJSON, and then create a copy using __geo_interface__.
>>> context = {'type': 'Point', 'coordinates': [0, 1]}
>>> geom = shape(context)
>>> geom.type == 'Point'
True
>>> geom.wkt
'POINT (0 1)'
>>> geom2 = shape(geom)
>>> geom == geom2
True
"""
if hasattr(context, "__geo_interface__"):
ob = context.__geo_interface__
else:
ob = context
geom_type = ob.get("type").lower()
if "coordinates" in ob and _is_coordinates_empty(ob["coordinates"]):
return _empty_shape_for_no_coordinates(geom_type)
elif geom_type == "point":
return Point(ob["coordinates"])
elif geom_type == "linestring":
return LineString(ob["coordinates"])
elif geom_type == "linearring":
return LinearRing(ob["coordinates"])
elif geom_type == "polygon":
return Polygon(ob["coordinates"][0], ob["coordinates"][1:])
elif geom_type == "multipoint":
return MultiPoint(ob["coordinates"])
elif geom_type == "multilinestring":
return MultiLineString(ob["coordinates"])
elif geom_type == "multipolygon":
return MultiPolygon([[c[0], c[1:]] for c in ob["coordinates"]])
elif geom_type == "geometrycollection":
geoms = [shape(g) for g in ob.get("geometries", [])]
return GeometryCollection(geoms)
else:
raise GeometryTypeError("Unknown geometry type: %s" % geom_type)
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 GeometryTypeError("First geometry must be a LineString")
if not isinstance(g2, LineString):
raise GeometryTypeError("Second geometry must be a LineString")
return shapely.shared_paths(g1, g2)
def _split_polygon_with_line(poly, splitter):
"""Split a Polygon with a LineString"""
if not isinstance(poly, Polygon):
raise GeometryTypeError("First argument must be a Polygon")
if not isinstance(splitter, LineString):
raise GeometryTypeError("Second argument must be a LineString")
union = poly.boundary.union(splitter)
# greatly improves split performance for big geometries with many
# holes (the following contains checks) with minimal overhead
# for common cases
poly = prep(poly)
# 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())
]
def _split_line_with_point(line, splitter):
"""Split a LineString with a Point"""
if not isinstance(line, LineString):
raise GeometryTypeError("First argument must be a LineString")
if not isinstance(splitter, Point):
raise GeometryTypeError("Second argument must be a 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
current_position = 0.0
for i in range(len(coords) - 1):
point1 = coords[i]
point2 = coords[i + 1]
dx = point1[0] - point2[0]
dy = point1[1] - point2[1]
segment_length = (dx**2 + dy**2)**0.5
current_position += segment_length
if distance_on_line == current_position:
# splitter is exactly on a vertex
return [LineString(coords[:i + 2]), LineString(coords[i + 1:])]
elif distance_on_line < current_position:
# splitter is between two vertices
return [
LineString(coords[:i + 1] + [splitter.coords[0]]),
LineString([splitter.coords[0]] + coords[i + 1:]),
]
return [line]
def dump_coords(geom):
"""Dump coordinates of a geometry in the same order as data packing"""
if not isinstance(geom, BaseGeometry):
raise ValueError("Must be instance of a geometry class; found " +
geom.__class__.__name__)
elif geom.type in ("Point", "LineString", "LinearRing"):
return geom.coords[:]
elif geom.type == "Polygon":
return geom.exterior.coords[:] + [i.coords[:] for i in geom.interiors]
elif geom.type.startswith("Multi") or geom.type == "GeometryCollection":
# Recursive call
return [dump_coords(part) for part in geom.geoms]
else:
raise GeometryTypeError("Unhandled geometry type: " + repr(geom.type))
def _empty_shape_for_no_coordinates(geom_type):
"""Return empty counterpart for geom_type"""
if geom_type == "point":
return Point()
elif geom_type == "multipoint":
return MultiPoint()
elif geom_type == "linestring":
return LineString()
elif geom_type == "multilinestring":
return MultiLineString()
elif geom_type == "polygon":
return Polygon()
elif geom_type == "multipolygon":
return MultiPolygon()
else:
raise GeometryTypeError("Unknown geometry type: %s" % geom_type)
def __getitem__(self, key):
m = self.__len__()
if isinstance(key, integer_types):
if key + m < 0 or key >= m:
raise IndexError("index out of range")
if key < 0:
i = m + key
else:
i = key
return self._get_geom_item(i)
elif isinstance(key, slice):
if type(self) == HeterogeneousGeometrySequence:
raise GeometryTypeError(
"Heterogeneous geometry collections are not sliceable")
res = []
start, stop, stride = key.indices(m)
for i in range(start, stop, stride):
res.append(self._get_geom_item(i))
return type(self.__p__)(res or None)
else:
raise TypeError("key must be an index or slice")
def asShape(context):
"""
Adapts the context to a geometry interface. The coordinates remain
stored in the context, and changes to them will be reflected in the
returned geometry object.
.. deprecated:: 1.8
The proxy geometries (adapter classes) created by this function are
deprecated, and this function will be removed in Shapely 2.0.
Use the `shape` function instead to convert a GeoJSON-like dict
to a Shapely geometry.
Parameters
----------
context :
a GeoJSON-like dict, which provides a "type" member describing the type
of the geometry and "coordinates" member providing a list of coordinates,
or an object which implements __geo_interface__.
Returns
-------
Geometry object
Notes
-----
The Adapter classes returned by this function trade performance for
reduced storage of coordinate values. In general, the shape() function
should be used instead.
Example
-------
Create a Point and Polygon from GeoJSON, change the coordinates of the Point's
context and show that the corresponding geometry is changed, as well.
>>> point_context = {'type': 'Point', 'coordinates': [0.5, 0.5]}
>>> poly_context = {'type': 'Polygon', 'coordinates': [[[0, 0], [1, 0], [1, 1], [0, 1], [0, 0]]]}
>>> point, poly = asShape(point_context), asShape(poly_context)
>>> poly.intersects(point)
True
>>> point_context['coordinates'][0] = 1.5
>>> poly.intersects(point)
False
"""
if hasattr(context, "__geo_interface__"):
ob = context.__geo_interface__
else:
ob = context
try:
geom_type = ob.get("type").lower()
except AttributeError:
raise ValueError("Context does not provide geo interface")
if geom_type == "point":
return asPoint(ob["coordinates"])
elif geom_type == "linestring":
return asLineString(ob["coordinates"])
elif geom_type == "polygon":
return asPolygon(ob["coordinates"][0], ob["coordinates"][1:])
elif geom_type == "multipoint":
return asMultiPoint(ob["coordinates"])
elif geom_type == "multilinestring":
return asMultiLineString(ob["coordinates"])
elif geom_type == "multipolygon":
return MultiPolygonAdapter(ob["coordinates"], context_type='geojson')
elif geom_type == "geometrycollection":
geoms = [asShape(g) for g in ob.get("geometries", [])]
if len(geoms) == 0:
# in this case no asShape call already raised the warning
warnings.warn(
"The proxy geometries (through the 'asShape()' constructor) "
"are deprecated and will be removed in Shapely 2.0. Use the "
"'shape()' function instead.",
ShapelyDeprecationWarning, stacklevel=2)
return GeometryCollection(geoms)
else:
raise GeometryTypeError("Unknown geometry type: %s" % geom_type)
def substring(geom, start_dist, end_dist, normalized=False):
"""Return a line segment between specified distances along a LineString
Negative distance values are taken as measured in the reverse
direction from the end of the geometry. Out-of-range index
values are handled by clamping them to the valid range of values.
If the start distance equals the end distance, a Point is returned.
If the start distance is actually beyond the end distance, then the
reversed substring is returned such that the start distance is
at the first coordinate.
Parameters
----------
geom : LineString
The geometry to get a substring of.
start_dist : float
The distance along `geom` of the start of the substring.
end_dist : float
The distance along `geom` of the end of the substring.
normalized : bool, False
Whether the distance parameters are interpreted as a
fraction of the geometry's length.
Returns
-------
Union[Point, LineString]
The substring between `start_dist` and `end_dist` or a Point
if they are at the same location.
Raises
------
TypeError
If `geom` is not a LineString.
Examples
--------
>>> from shapely.geometry import LineString
>>> from shapely.ops import substring
>>> ls = LineString((i, 0) for i in range(6))
>>> ls.wkt
'LINESTRING (0 0, 1 0, 2 0, 3 0, 4 0, 5 0)'
>>> substring(ls, start_dist=1, end_dist=3).wkt
'LINESTRING (1 0, 2 0, 3 0)'
>>> substring(ls, start_dist=3, end_dist=1).wkt
'LINESTRING (3 0, 2 0, 1 0)'
>>> substring(ls, start_dist=1, end_dist=-3).wkt
'LINESTRING (1 0, 2 0)'
>>> substring(ls, start_dist=0.2, end_dist=-0.6, normalized=True).wkt
'LINESTRING (1 0, 2 0)'
Returning a `Point` when `start_dist` and `end_dist` are at the
same location.
>>> substring(ls, 2.5, -2.5).wkt
'POINT (2.5 0)'
"""
if not isinstance(geom, LineString):
raise GeometryTypeError(
"Can only calculate a substring of LineString geometries. A %s was provided."
% geom.type)
# Filter out cases in which to return a point
if start_dist == end_dist:
return geom.interpolate(start_dist, normalized)
elif not normalized and start_dist >= geom.length and end_dist >= geom.length:
return geom.interpolate(geom.length, normalized)
elif not normalized and -start_dist >= geom.length and -end_dist >= geom.length:
return geom.interpolate(0, normalized)
elif normalized and start_dist >= 1 and end_dist >= 1:
return geom.interpolate(1, normalized)
elif normalized and -start_dist >= 1 and -end_dist >= 1:
return geom.interpolate(0, normalized)
if normalized:
start_dist *= geom.length
end_dist *= geom.length
# Filter out cases where distances meet at a middle point from opposite ends.
if start_dist < 0 < end_dist and abs(start_dist) + end_dist == geom.length:
return geom.interpolate(end_dist)
elif end_dist < 0 < start_dist and abs(
end_dist) + start_dist == geom.length:
return geom.interpolate(start_dist)
start_point = geom.interpolate(start_dist)
end_point = geom.interpolate(end_dist)
if start_dist < 0:
start_dist = geom.length + start_dist # Values may still be negative,
if end_dist < 0: # but only in the out-of-range
end_dist = geom.length + end_dist # sense, not the wrap-around sense.
reverse = start_dist > end_dist
if reverse:
start_dist, end_dist = end_dist, start_dist
if start_dist < 0:
start_dist = 0 # to avoid duplicating the first vertex
if reverse:
vertex_list = [(end_point.x, end_point.y)]
else:
vertex_list = [(start_point.x, start_point.y)]
coords = list(geom.coords)
current_distance = 0
for p1, p2 in zip(coords, coords[1:]):
if start_dist < current_distance < end_dist:
vertex_list.append(p1)
elif current_distance >= end_dist:
break
current_distance += ((p2[0] - p1[0])**2 + (p2[1] - p1[1])**2)**0.5
if reverse:
vertex_list.append((start_point.x, start_point.y))
# reverse direction result
vertex_list = reversed(vertex_list)
else:
vertex_list.append((end_point.x, end_point.y))
return LineString(vertex_list)
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 GeometryTypeError(
"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 GeometryTypeError(
"Splitting a Polygon with a %s is not supported" %
splitter.type)
else:
raise GeometryTypeError("Splitting %s geometry is not supported" %
geom.type)
return GeometryCollection(split_func(geom, splitter))
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)
Using pyproj >= 2.1, this example will accurately project Shapely geometries:
import pyproj
wgs84 = pyproj.CRS('EPSG:4326')
utm = pyproj.CRS('EPSG:32618')
project = pyproj.Transformer.from_crs(wgs84, utm, always_xy=True).transform
g2 = transform(project, g1)
Note that the always_xy kwarg is required here as Shapely geometries only support
X,Y coordinate ordering.
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(*zip(*geom.coords))))
elif geom.type == "Polygon":
shell = type(geom.exterior)(
zip(*func(*zip(*geom.exterior.coords))))
holes = list(
type(ring)(zip(*func(*zip(*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 GeometryTypeError("Type %r not recognized" % geom.type)
def affine_transform(geom, matrix):
r"""Returns a transformed geometry using an affine transformation matrix.
The coefficient matrix is provided as a list or tuple with 6 or 12 items
for 2D or 3D transformations, respectively.
For 2D affine transformations, the 6 parameter matrix is::
[a, b, d, e, xoff, yoff]
which represents the augmented matrix::
[x'] / a b xoff \ [x]
[y'] = | d e yoff | [y]
[1 ] \ 0 0 1 / [1]
or the equations for the transformed coordinates::
x' = a * x + b * y + xoff
y' = d * x + e * y + yoff
For 3D affine transformations, the 12 parameter matrix is::
[a, b, c, d, e, f, g, h, i, xoff, yoff, zoff]
which represents the augmented matrix::
[x'] / a b c xoff \ [x]
[y'] = | d e f yoff | [y]
[z'] | g h i zoff | [z]
[1 ] \ 0 0 0 1 / [1]
or the equations for the transformed coordinates::
x' = a * x + b * y + c * z + xoff
y' = d * x + e * y + f * z + yoff
z' = g * x + h * y + i * z + zoff
"""
if geom.is_empty:
return geom
if len(matrix) == 6:
ndim = 2
a, b, d, e, xoff, yoff = matrix
if geom.has_z:
ndim = 3
i = 1.0
c = f = g = h = zoff = 0.0
matrix = a, b, c, d, e, f, g, h, i, xoff, yoff, zoff
elif len(matrix) == 12:
ndim = 3
a, b, c, d, e, f, g, h, i, xoff, yoff, zoff = matrix
if not geom.has_z:
ndim = 2
matrix = a, b, d, e, xoff, yoff
else:
raise ValueError("'matrix' expects either 6 or 12 coefficients")
def affine_pts(pts):
"""Internal function to yield affine transform of coordinate tuples"""
if ndim == 2:
for x, y in pts:
xp = a * x + b * y + xoff
yp = d * x + e * y + yoff
yield (xp, yp)
elif ndim == 3:
for x, y, z in pts:
xp = a * x + b * y + c * z + xoff
yp = d * x + e * y + f * z + yoff
zp = g * x + h * y + i * z + zoff
yield (xp, yp, zp)
# Process coordinates from each supported geometry type
if geom.type in ('Point', 'LineString', 'LinearRing'):
return type(geom)(list(affine_pts(geom.coords)))
elif geom.type == 'Polygon':
ring = geom.exterior
shell = type(ring)(list(affine_pts(ring.coords)))
holes = list(geom.interiors)
for pos, ring in enumerate(holes):
holes[pos] = type(ring)(list(affine_pts(ring.coords)))
return type(geom)(shell, holes)
elif geom.type.startswith('Multi') or geom.type == 'GeometryCollection':
# Recursive call
# TODO: fix GeometryCollection constructor
return type(geom)(
[affine_transform(part, matrix) for part in geom.geoms])
else:
raise GeometryTypeError('Type %r not recognized' % geom.type)
def _validate_line(self, ob):
super()._validate(ob)
if not ob.geom_type in ['LinearRing', 'LineString', 'MultiLineString']:
raise GeometryTypeError("Only linear types support this operation")