"""Linear geometry functions."""
from shapely import lib
from shapely.decorators import deprecate_positional, multithreading_enabled
from shapely.errors import UnsupportedGEOSVersionError
__all__ = [
"line_interpolate_point",
"line_locate_point",
"line_merge",
"shared_paths",
"shortest_line",
]
# Note: future plan is to change this signature over a few releases:
# shapely 2.0:
# line_interpolate_point(line, distance, normalized=False, **kwargs)
# shapely 2.1: shows deprecation warning about positional 'normalized' arg
# same signature as 2.0
# shapely 2.2(?): enforce keyword-only arguments after 'normalized'
# line_interpolate_point(line, distance, *, normalized=False, **kwargs)
@deprecate_positional(["normalized"], category=DeprecationWarning)
@multithreading_enabled
def line_interpolate_point(line, distance, normalized=False, **kwargs):
"""Return a point interpolated at given distance on a line.
Parameters
----------
line : Geometry or array_like
For multilinestrings or geometrycollections, the first geometry is taken
and the rest is ignored. This function raises a TypeError for non-linear
geometries. For empty linear geometries, empty points are returned.
distance : float or array_like
Negative values measure distance from the end of the line. Out-of-range
values will be clipped to the line endings.
normalized : bool, default False
If True, the distance is a fraction of the total
line length instead of the absolute distance.
**kwargs
See :ref:`NumPy ufunc docs <ufuncs.kwargs>` for other keyword arguments.
Examples
--------
>>> import shapely
>>> from shapely import LineString
>>> line = LineString([(0, 2), (0, 10)])
>>> shapely.line_interpolate_point(line, 2)
<POINT (0 4)>
>>> shapely.line_interpolate_point(line, 100)
<POINT (0 10)>
>>> shapely.line_interpolate_point(line, -2)
<POINT (0 8)>
>>> shapely.line_interpolate_point(line, [0.25, -0.25], normalized=True).tolist()
[<POINT (0 4)>, <POINT (0 8)>]
>>> shapely.line_interpolate_point(LineString(), 1)
<POINT EMPTY>
"""
if normalized:
return lib.line_interpolate_point_normalized(line, distance)
else:
return lib.line_interpolate_point(line, distance)
# Note: future plan is to change this signature over a few releases:
# shapely 2.0:
# line_locate_point(line, other, normalized=False, **kwargs)
# shapely 2.1: shows deprecation warning about positional 'normalized' arg
# same signature as 2.0
# shapely 2.2(?): enforce keyword-only arguments after 'normalized'
# line_locate_point(line, other, *, normalized=False, **kwargs)
@deprecate_positional(["normalized"], category=DeprecationWarning)
@multithreading_enabled
def line_locate_point(line, other, normalized=False, **kwargs):
"""Return the distance to the line origin of given point.
If given point does not intersect with the line, the point will first be
projected onto the line after which the distance is taken.
Parameters
----------
line : Geometry or array_like
Line or lines to calculate the distance to.
other : Geometry or array_like
Point or points to calculate the distance from.
normalized : bool, default False
If True, the distance is a fraction of the total line length instead of
the absolute distance.
**kwargs
See :ref:`NumPy ufunc docs <ufuncs.kwargs>` for other keyword arguments.
Examples
--------
>>> import shapely
>>> from shapely import LineString, Point
>>> line = LineString([(0, 2), (0, 10)])
>>> point = Point(4, 4)
>>> shapely.line_locate_point(line, point)
2.0
>>> shapely.line_locate_point(line, point, normalized=True)
0.25
>>> shapely.line_locate_point(line, Point(0, 18))
8.0
>>> shapely.line_locate_point(LineString(), point)
nan
"""
if normalized:
return lib.line_locate_point_normalized(line, other)
else:
return lib.line_locate_point(line, other)
@multithreading_enabled
def line_merge(line, directed=False, **kwargs):
"""Return (Multi)LineStrings formed by combining the lines in a MultiLineString.
Lines are joined together at their endpoints in case two lines are
intersecting. Lines are not joined when 3 or more lines are intersecting at
the endpoints. Line elements that cannot be joined are kept as is in the
resulting MultiLineString.
The direction of each merged LineString will be that of the majority of the
LineStrings from which it was derived. Except if ``directed=True`` is
specified, then the operation will not change the order of points within
lines and so only lines which can be joined with no change in direction
are merged.
Parameters
----------
line : Geometry or array_like
Linear geometry or geometries to merge.
directed : bool, default False
Only combine lines if possible without changing point order.
Requires GEOS >= 3.11.0
**kwargs
See :ref:`NumPy ufunc docs <ufuncs.kwargs>` for other keyword arguments.
Examples
--------
>>> import shapely
>>> from shapely import MultiLineString
>>> shapely.line_merge(MultiLineString([[(0, 2), (0, 10)], [(0, 10), (5, 10)]]))
<LINESTRING (0 2, 0 10, 5 10)>
>>> shapely.line_merge(MultiLineString([[(0, 2), (0, 10)], [(0, 11), (5, 10)]]))
<MULTILINESTRING ((0 2, 0 10), (0 11, 5 10))>
>>> shapely.line_merge(MultiLineString())
<GEOMETRYCOLLECTION EMPTY>
>>> shapely.line_merge(MultiLineString([[(0, 0), (1, 0)], [(0, 0), (3, 0)]]))
<LINESTRING (1 0, 0 0, 3 0)>
>>> shapely.line_merge(MultiLineString([[(0, 0), (1, 0)], [(0, 0), (3, 0)]]), \
directed=True)
<MULTILINESTRING ((0 0, 1 0), (0 0, 3 0))>
"""
if directed:
if lib.geos_version < (3, 11, 0):
raise UnsupportedGEOSVersionError(
"'{}' requires at least GEOS {}.{}.{}.".format(
"line_merge", *(3, 11, 0)
)
)
return lib.line_merge_directed(line, **kwargs)
return lib.line_merge(line, **kwargs)
@multithreading_enabled
def shared_paths(a, b, **kwargs):
"""Return the shared paths between a and b.
Both geometries should be linestrings or arrays of linestrings.
A geometrycollection or array of geometrycollections is returned
with two elements in each geometrycollection. The first element is a
multilinestring containing shared paths with the same direction
for both inputs. The second element is a multilinestring containing
shared paths with the opposite direction for the two inputs.
Parameters
----------
a, b : Geometry or array_like
Linestring or linestrings to compare.
**kwargs
See :ref:`NumPy ufunc docs <ufuncs.kwargs>` for other keyword arguments.
Examples
--------
>>> import shapely
>>> from shapely import LineString
>>> line1 = LineString([(0, 0), (1, 0), (1, 1), (0, 1), (0, 0)])
>>> line2 = LineString([(1, 0), (2, 0), (2, 1), (1, 1), (1, 0)])
>>> shapely.shared_paths(line1, line2).wkt
'GEOMETRYCOLLECTION (MULTILINESTRING EMPTY, MULTILINESTRING ((1 0, 1 1)))'
>>> line3 = LineString([(1, 1), (0, 1)])
>>> shapely.shared_paths(line1, line3).wkt
'GEOMETRYCOLLECTION (MULTILINESTRING ((1 1, 0 1)), MULTILINESTRING EMPTY)'
"""
return lib.shared_paths(a, b, **kwargs)
@multithreading_enabled
def shortest_line(a, b, **kwargs):
"""Return the shortest line between two geometries.
The resulting line consists of two points, representing the nearest
points between the geometry pair. The line always starts in the first
geometry `a` and ends in the second geometry `b`. The endpoints of the
line will not necessarily be existing vertices of the input geometries
`a` and `b`, but can also be a point along a line segment.
Parameters
----------
a, b : Geometry or array_like
Geometry or geometries to compare.
**kwargs
See :ref:`NumPy ufunc docs <ufuncs.kwargs>` for other keyword arguments.
See Also
--------
prepare : improve performance by preparing ``a`` (the first argument)
Examples
--------
>>> import shapely
>>> from shapely import LineString
>>> line1 = LineString([(0, 0), (1, 0), (1, 1), (0, 1), (0, 0)])
>>> line2 = LineString([(0, 3), (3, 0), (5, 3)])
>>> shapely.shortest_line(line1, line2)
<LINESTRING (1 1, 1.5 1.5)>
"""
return lib.shortest_line(a, b, **kwargs)