"""
Computational geometry code for PySAL: Python Spatial Analysis Library.
"""
__author__ = "Sergio J. Rey, Xinyue Ye, Charles Schmidt, Andrew Winslow, Hu Shao"
# ruff: noqa: A003, N802, E402
import math
import warnings
from .sphere import arcdist
__all__ = [
"Point",
"LineSegment",
"Line",
"Ray",
"Chain",
"Polygon",
"Rectangle",
"asShape",
]
dep_msg = (
"Objects based on the `Geometry` class will deprecated "
"and removed in a future version of libpysal."
)
[docs]
def asShape(obj):
"""Returns a PySAL shape object from ``obj``, which
must support the ``__geo_interface__``.
Parameters
----------
obj : {libpysal.cg.{Point, LineSegment, Line, Ray, Chain, Polygon}
A geometric representation of an object.
Raises
------
TypeError
Raised when ``obj`` is not a supported shape.
NotImplementedError
Raised when ``geo_type`` is not a supported type.
Returns
-------
obj : {libpysal.cg.{Point, LineSegment, Line, Ray, Chain, Polygon}
A new geometric representation of the object.
"""
if isinstance(obj, Point | LineSegment | Line | Ray | Chain | Polygon):
pass
else:
geo = obj.__geo_interface__ if hasattr(obj, "__geo_interface__") else obj
if hasattr(geo, "type"):
raise TypeError("%r does not appear to be a shape object." % (obj))
geo_type = geo["type"].lower()
# if geo_type.startswith('multi'):
# raise NotImplementedError, "%s are not supported at this time."%geo_type
if geo_type in _geoJSON_type_to_Pysal_type:
obj = _geoJSON_type_to_Pysal_type[geo_type].__from_geo_interface__(geo)
else:
raise NotImplementedError("%s is not supported at this time." % geo_type)
return obj
class Geometry:
"""A base class to help implement ``is_geometry``
and make geometric types extendable.
"""
def __init__(self):
pass
[docs]
class Point(Geometry):
"""Geometric class for point objects.
Parameters
----------
loc : tuple
The point's location (number :math:`x`-tuple, :math:`x` > 1).
Examples
--------
>>> p = Point((1, 3))
"""
[docs]
def __init__(self, loc):
warnings.warn(dep_msg, FutureWarning, stacklevel=2)
self.__loc = tuple(map(float, loc))
@classmethod
def __from_geo_interface__(cls, geo):
return cls(geo["coordinates"])
@property
def __geo_interface__(self):
return {"type": "Point", "coordinates": self.__loc}
def __lt__(self, other) -> bool:
"""Tests if the point is less than another object.
Parameters
----------
other : libpysal.cg.Point
An object to test equality against.
Examples
--------
>>> Point((0, 1)) < Point((0, 1))
False
>>> Point((0, 1)) < Point((1, 1))
True
"""
return (self.__loc) < (other.__loc)
def __le__(self, other) -> bool:
"""Tests if the point is less than or equal to another object.
Parameters
----------
other : libpysal.cg.Point
An object to test equality against.
Examples
--------
>>> Point((0, 1)) <= Point((0, 1))
True
>>> Point((0, 1)) <= Point((1, 1))
True
"""
return (self.__loc) <= (other.__loc)
def __eq__(self, other) -> bool:
"""Tests if the point is equal to another object.
Parameters
----------
other : libpysal.cg.Point
An object to test equality against.
Examples
--------
>>> Point((0, 1)) == Point((0, 1))
True
>>> Point((0, 1)) == Point((1, 1))
False
"""
try:
return (self.__loc) == (other.__loc)
except AttributeError:
return False
def __ne__(self, other) -> bool:
"""Tests if the point is not equal to another object.
Parameters
----------
other : libpysal.cg.Point
An object to test equality against.
Examples
--------
>>> Point((0, 1)) != Point((0, 1))
False
>>> Point((0, 1)) != Point((1, 1))
True
"""
try:
return (self.__loc) != (other.__loc)
except AttributeError:
return True
def __gt__(self, other) -> bool:
"""Tests if the point is greater than another object.
Parameters
----------
other : libpysal.cg.Point
An object to test equality against.
Examples
--------
>>> Point((0, 1)) > Point((0, 1))
False
>>> Point((0, 1)) > Point((1, 1))
False
"""
return (self.__loc) > (other.__loc)
def __ge__(self, other) -> bool:
"""Tests if the point is greater than or equal to another object.
Parameters
----------
other : libpysal.cg.Point
An object to test equality against.
Examples
--------
>>> Point((0, 1)) >= Point((0, 1))
True
>>> Point((0, 1)) >= Point((1, 1))
False
"""
return (self.__loc) >= (other.__loc)
def __hash__(self) -> int:
"""Returns the hash of the point's location.
Examples
--------
>>> hash(Point((0, 1))) == hash(Point((0, 1)))
True
>>> hash(Point((0, 1))) == hash(Point((1, 1)))
False
"""
return hash(self.__loc)
def __getitem__(self, *args) -> int | float:
"""Return the coordinate for the given dimension.
Parameters
----------
*args : tuple
A singleton tuple of :math:`(i)` with :math:`i`
as the index of the desired dimension.
Examples
--------
>>> p = Point((5.5, 4.3))
>>> p[0] == 5.5
True
>>> p[1] == 4.3
True
"""
return self.__loc.__getitem__(*args)
def __getslice__(self, *args) -> slice:
"""Return the coordinates for the given dimensions.
Parameters
----------
*args : tuple
A tuple of :math:`(i,j)` with :math:`i` as the index to the start
slice and :math:`j` as the index to end the slice (excluded).
Examples
--------
>>> p = Point((3, 6, 2))
>>> p[:2] == (3, 6)
True
>>> p[1:2] == (6,)
True
"""
return self.__loc.__getslice__(*args)
def __len__(self) -> int:
"""Returns the dimensions of the point.
Examples
--------
>>> len(Point((1, 2)))
2
"""
return len(self.__loc)
def __repr__(self) -> str:
"""Returns the string representation of the ``Point``.
Examples
--------
>>> Point((0, 1))
(0.0, 1.0)
"""
return str(self)
def __str__(self) -> str:
"""Returns a string representation of a ``Point`` object.
Examples
--------
>>> p = Point((1, 3))
>>> str(p)
'(1.0, 3.0)'
"""
return str(self.__loc)
# return "POINT ({} {})".format(*self.__loc)
[docs]
class LineSegment(Geometry):
"""Geometric representation of line segment objects.
Parameters
----------
start_pt : libpysal.cg.Point
The point where the segment begins.
end_pt : libpysal.cg.Point
The point where the segment ends.
Attributes
----------
p1 : libpysal.cg.Point
The starting point of the line segment.
p2 : Point
The ending point of the line segment.
bounding_box : libpysal.cg.Rectangle
The bounding box of the segment.
len : float
The length of the segment.
line : libpysal.cg.Line
The line on which the segment lies.
Examples
--------
>>> ls = LineSegment(Point((1, 2)), Point((5, 6)))
"""
[docs]
def __init__(self, start_pt, end_pt):
warnings.warn(dep_msg, FutureWarning, stacklevel=2)
self._p1 = start_pt
self._p2 = end_pt
self._reset_props()
def __str__(self):
return "LineSegment(" + str(self._p1) + ", " + str(self._p2) + ")"
# return "LINESTRING ({} {}, {} {})".format(
# self._p1[0], self._p1[1], self._p2[0], self._p2[1]
# )
def __eq__(self, other) -> bool:
"""Returns ``True`` if ``self`` and ``other`` are the same line segment.
Examples
--------
>>> l1 = LineSegment(Point((1, 2)), Point((5, 6)))
>>> l2 = LineSegment(Point((5, 6)), Point((1, 2)))
>>> l1 == l2
True
>>> l2 == l1
True
"""
eq = False
if not isinstance(other, self.__class__):
pass
else:
if (other.p1 == self._p1 and other.p2 == self._p2) or (
other.p2 == self._p1 and other.p1 == self._p2
):
eq = True
return eq
[docs]
def intersect(self, other) -> bool:
"""Test whether segment intersects with other segment (``True``) or
not (``False``). Handles endpoints of segments being on other segment.
Parameters
----------
other : libpysal.cg.LineSegment
Another line segment to check against.
Examples
--------
>>> ls = LineSegment(Point((5, 0)), Point((10, 0)))
>>> ls1 = LineSegment(Point((5, 0)), Point((10, 1)))
>>> ls.intersect(ls1)
True
>>> ls2 = LineSegment(Point((5, 1)), Point((10, 1)))
>>> ls.intersect(ls2)
False
>>> ls2 = LineSegment(Point((7, -1)), Point((7, 2)))
>>> ls.intersect(ls2)
True
"""
ccw1 = self.sw_ccw(other.p2)
ccw2 = self.sw_ccw(other.p1)
ccw3 = other.sw_ccw(self.p1)
ccw4 = other.sw_ccw(self.p2)
intersects = ccw1 * ccw2 <= 0 and ccw3 * ccw4 <= 0
return intersects
def _reset_props(self):
"""**HELPER METHOD. DO NOT CALL.**
Resets attributes which are functions of other attributes.
The getters for these attributes (implemented as properties)
then recompute their values if they have been reset since
the last call to the getter.
Examples
--------
>>> ls = LineSegment(Point((1, 2)), Point((5, 6)))
>>> ls._reset_props()
"""
self._bounding_box = None
self._len = None
self._line = False
def _get_p1(self):
"""**HELPER METHOD. DO NOT CALL.**
Returns the ``p1`` attribute of the line segment.
Returns
-------
self._p1 : libpysal.cg.Point
The ``_p1`` attribute.
Examples
--------
>>> ls = LineSegment(Point((1, 2)), Point((5, 6)))
>>> r = ls._get_p1()
>>> r == Point((1, 2))
True
"""
return self._p1
def _set_p1(self, p1):
"""**HELPER METHOD. DO NOT CALL.**
Sets the ``p1`` attribute of the line segment.
Parameters
----------
p1 : libpysal.cg.Point
A point.
Returns
-------
self._p1 : libpysal.cg.Point
The reset ``p1`` attribute.
Examples
--------
>>> ls = LineSegment(Point((1, 2)), Point((5, 6)))
>>> r = ls._set_p1(Point((3, -1)))
>>> r == Point((3.0, -1.0))
True
"""
self._p1 = p1
self._reset_props()
return self._p1
p1 = property(_get_p1, _set_p1)
def _get_p2(self):
"""**HELPER METHOD. DO NOT CALL.**
Returns the ``p2`` attribute of the line segment.
Returns
-------
self._p2 : libpysal.cg.Point
The ``_p2`` attribute.
Examples
--------
>>> ls = LineSegment(Point((1, 2)), Point((5, 6)))
>>> r = ls._get_p2()
>>> r == Point((5, 6))
True
"""
return self._p2
def _set_p2(self, p2):
"""**HELPER METHOD. DO NOT CALL.**
Sets the ``p2`` attribute of the line segment.
Parameters
----------
p2 : libpysal.cg.Point
A point.
Returns
-------
self._p2 : libpysal.cg.Point
The reset ``p2`` attribute.
Examples
--------
>>> ls = LineSegment(Point((1, 2)), Point((5, 6)))
>>> r = ls._set_p2(Point((3, -1)))
>>> r == Point((3.0, -1.0))
True
"""
self._p2 = p2
self._reset_props()
return self._p2
p2 = property(_get_p2, _set_p2)
[docs]
def is_ccw(self, pt) -> bool:
"""Returns whether a point is counterclockwise of the
segment (``True``) or not (``False``). Exclusive.
Parameters
----------
pt : libpysal.cg.Point
A point lying ccw or cw of a segment.
Examples
--------
>>> ls = LineSegment(Point((0, 0)), Point((5, 0)))
>>> ls.is_ccw(Point((2, 2)))
True
>>> ls.is_ccw(Point((2, -2)))
False
"""
v1 = (self._p2[0] - self._p1[0], self._p2[1] - self._p1[1])
v2 = (pt[0] - self._p1[0], pt[1] - self._p1[1])
return v1[0] * v2[1] - v1[1] * v2[0] > 0
[docs]
def is_cw(self, pt) -> bool:
"""Returns whether a point is clockwise of the
segment (``True``) or not (``False``). Exclusive.
Parameters
----------
pt : libpysal.cg.Point
A point lying ccw or cw of a segment.
Examples
--------
>>> ls = LineSegment(Point((0, 0)), Point((5, 0)))
>>> ls.is_cw(Point((2, 2)))
False
>>> ls.is_cw(Point((2, -2)))
True
"""
v1 = (self._p2[0] - self._p1[0], self._p2[1] - self._p1[1])
v2 = (pt[0] - self._p1[0], pt[1] - self._p1[1])
return v1[0] * v2[1] - v1[1] * v2[0] < 0
[docs]
def sw_ccw(self, pt):
"""Sedgewick test for ``pt`` being ccw of segment.
Returns
-------
is_ccw : bool
``1`` if turn from ``self.p1`` to ``self.p2`` to ``pt`` is ccw.
``-1`` if turn from ``self.p1`` to ``self.p2`` to ``pt`` is cw.
``-1`` if the points are collinear and ``self.p1`` is in the middle.
``1`` if the points are collinear and ``self.p2`` is in the middle.
``0`` if the points are collinear and ``pt`` is in the middle.
"""
p0 = self.p1
p1 = self.p2
p2 = pt
dx1 = p1[0] - p0[0]
dy1 = p1[1] - p0[1]
dx2 = p2[0] - p0[0]
dy2 = p2[1] - p0[1]
if dy1 * dx2 < dy2 * dx1:
is_ccw = 1
elif (dy1 * dx2 > dy2 * dx1) or (dx1 * dx2 < 0 or dy1 * dy2 < 0):
is_ccw = -1
elif dx1 * dx1 + dy1 * dy1 >= dx2 * dx2 + dy2 * dy2:
is_ccw = 0
else:
is_ccw = 1
return is_ccw
[docs]
def get_swap(self):
"""Returns a ``LineSegment`` object which has its endpoints swapped.
Returns
-------
line_seg : libpysal.cg.LineSegment
The ``LineSegment`` object which has its endpoints swapped.
Examples
--------
>>> ls = LineSegment(Point((1, 2)), Point((5, 6)))
>>> swap = ls.get_swap()
>>> swap.p1[0]
5.0
>>> swap.p1[1]
6.0
>>> swap.p2[0]
1.0
>>> swap.p2[1]
2.0
"""
line_seg = LineSegment(self._p2, self._p1)
return line_seg
@property
def bounding_box(self):
"""Returns the minimum bounding box of a ``LineSegment`` object.
Returns
-------
self._bounding_box : libpysal.cg.Rectangle
The bounding box of the line segment.
Examples
--------
>>> ls = LineSegment(Point((1, 2)), Point((5, 6)))
>>> ls.bounding_box.left
1.0
>>> ls.bounding_box.lower
2.0
>>> ls.bounding_box.right
5.0
>>> ls.bounding_box.upper
6.0
"""
# If LineSegment attributes p1, p2 changed, recompute
if self._bounding_box is None:
self._bounding_box = Rectangle(
min([self._p1[0], self._p2[0]]),
min([self._p1[1], self._p2[1]]),
max([self._p1[0], self._p2[0]]),
max([self._p1[1], self._p2[1]]),
)
return Rectangle(
self._bounding_box.left,
self._bounding_box.lower,
self._bounding_box.right,
self._bounding_box.upper,
)
@property
def len(self) -> float:
"""Returns the length of a ``LineSegment`` object.
Examples
--------
>>> ls = LineSegment(Point((2, 2)), Point((5, 2)))
>>> ls.len
3.0
"""
# If LineSegment attributes p1, p2 changed, recompute
if self._len is None:
self._len = math.hypot(self._p1[0] - self._p2[0], self._p1[1] - self._p2[1])
return self._len
@property
def line(self):
"""Returns a ``Line`` object of the line on which the segment lies.
Returns
-------
self._line : libpysal.cg.Line
The ``Line`` object of the line on which the segment lies.
Examples
--------
>>> ls = LineSegment(Point((2, 2)), Point((3, 3)))
>>> l = ls.line
>>> l.m
1.0
>>> l.b
0.0
"""
if self._line is False:
dx = self._p1[0] - self._p2[0]
dy = self._p1[1] - self._p2[1]
if dx == 0 and dy == 0:
self._line = None
elif dx == 0:
self._line = VerticalLine(self._p1[0])
else:
m = dy / float(dx)
# y - mx
b = self._p1[1] - m * self._p1[0]
self._line = Line(m, b)
return self._line
class VerticalLine(Geometry):
"""Geometric representation of verticle line objects.
Parameters
----------
x : {int, float}
The :math:`x`-intercept of the line. ``x`` is also an attribute.
Examples
--------
>>> ls = VerticalLine(0)
>>> ls.m
inf
>>> ls.b
nan
"""
def __init__(self, x):
warnings.warn(dep_msg, FutureWarning, stacklevel=2)
self._x = float(x)
self.m = float("inf")
self.b = float("nan")
def x(self, y) -> float: # noqa: ARG002
"""Returns the :math:`x`-value of the line at a particular :math:`y`-value.
Parameters
----------
y : {int, float}
The :math:`y`-value at which to compute :math:`x`.
Examples
--------
>>> l = VerticalLine(0)
>>> l.x(0.25)
0.0
"""
return self._x
def y(self, x) -> float: # noqa: ARG002
"""Returns the :math:`y`-value of the line at a particular :math:`x`-value.
Parameters
----------
x : {int, float}
The :math:`x`-value at which to compute :math:`y`.
Examples
--------
>>> l = VerticalLine(1)
>>> l.y(1)
nan
"""
return float("nan")
[docs]
class Line(Geometry):
"""Geometric representation of line objects.
Parameters
----------
m : {int, float}
The slope of the line. ``m`` is also an attribute.
b : {int, float}
The :math:`y`-intercept of the line. ``b`` is also an attribute.
Raises
------
ArithmeticError
Raised when infinity is passed in as the slope.
Examples
--------
>>> ls = Line(1, 0)
>>> ls.m
1.0
>>> ls.b
0.0
"""
[docs]
def __init__(self, m, b):
warnings.warn(dep_msg, FutureWarning, stacklevel=2)
if m == float("inf"):
raise ArithmeticError("Slope cannot be infinite.")
self.m = float(m)
self.b = float(b)
[docs]
def x(self, y: int | float) -> float:
"""Returns the :math:`x`-value of the line at a particular :math:`y`-value.
Parameters
----------
y : {int, float}
The :math:`y`-value at which to compute :math:`x`.
Raises
------
ArithmeticError
Raised when ``0.`` is passed in as the slope.
Examples
--------
>>> l = Line(0.5, 0)
>>> l.x(0.25)
0.5
"""
if self.m == 0:
raise ArithmeticError("Cannot solve for 'x' when slope is zero.")
return (y - self.b) / self.m
[docs]
def y(self, x: int | float) -> float:
"""Returns the :math:`y`-value of the line at a particular :math:`x`-value.
Parameters
----------
x : {int, float}
The :math:`x`-value at which to compute :math:`y`.
Examples
--------
>>> l = Line(1, 0)
>>> l.y(1)
1.0
"""
if self.m == 0:
return self.b
return self.m * x + self.b
[docs]
class Ray:
"""Geometric representation of ray objects.
Parameters
----------
origin : libpysal.cg.Point
The point where the ray originates.
second_p :
The second point specifying the ray (not ``origin``.)
Attributes
----------
o : libpysal.cg.Point
The origin (point where ray originates). See ``origin``.
p : libpysal.cg.Point
The second point on the ray (not the point where the
ray originates). See ``second_p``.
Examples
--------
>>> l = Ray(Point((0, 0)), Point((1, 0)))
>>> str(l.o)
'(0.0, 0.0)'
>>> str(l.p)
'(1.0, 0.0)'
"""
[docs]
def __init__(self, origin, second_p):
warnings.warn(dep_msg, FutureWarning, stacklevel=2)
self.o = origin
self.p = second_p
[docs]
class Chain(Geometry):
"""Geometric representation of a chain, also known as a polyline.
Parameters
----------
vertices : list
A point list or list of point lists.
Attributes
----------
vertices : list
The list of points of the vertices of the chain in order.
len : float
The geometric length of the chain.
Examples
--------
>>> c = Chain([Point((0, 0)), Point((1, 0)), Point((1, 1)), Point((2, 1))])
"""
[docs]
def __init__(self, vertices: list):
warnings.warn(dep_msg, FutureWarning, stacklevel=2)
if isinstance(vertices[0], list):
self._vertices = list(vertices)
else:
self._vertices = [vertices]
self._reset_props()
@classmethod
def __from_geo_interface__(cls, geo: dict):
if geo["type"].lower() == "linestring":
verts = [Point(pt) for pt in geo["coordinates"]]
elif geo["type"].lower() == "multilinestring":
verts = [list(map(Point, part)) for part in geo["coordinates"]]
else:
raise TypeError("%r is not a Chain." % geo)
return cls(verts)
@property
def __geo_interface__(self) -> dict:
if len(self.parts) == 1:
return {"type": "LineString", "coordinates": self.vertices}
else:
return {"type": "MultiLineString", "coordinates": self.parts}
def _reset_props(self):
"""**HELPER METHOD. DO NOT CALL.** Resets attributes which are
functions of other attributes. The ``getter``s for these attributes
(implemented as ``properties``) then recompute their values if they
have been reset since the last call to the ``getter``.
"""
self._len = None
self._arclen = None
self._bounding_box = None
@property
def vertices(self) -> list:
"""Returns the vertices of the chain in clockwise order.
Examples
--------
>>> c = Chain([Point((0, 0)), Point((1, 0)), Point((1, 1)), Point((2, 1))])
>>> verts = c.vertices
>>> len(verts)
4
"""
return sum(list(self._vertices), [])
@property
def parts(self) -> list:
"""Returns the parts (lists of ``libpysal.cg.Point`` objects) of the chain.
Examples
--------
>>> c = Chain(
... [
... [Point((0, 0)), Point((1, 0)), Point((1, 1)), Point((0, 1))],
... [Point((2, 1)), Point((2, 2)), Point((1, 2)), Point((1, 1))]
... ]
... )
>>> len(c.parts)
2
"""
return [list(part) for part in self._vertices]
@property
def bounding_box(self):
"""Returns the bounding box of the chain.
Returns
-------
self._bounding_box : libpysal.cg.Rectangle
The bounding box of the chain.
Examples
--------
>>> c = Chain([Point((0, 0)), Point((2, 0)), Point((2, 1)), Point((0, 1))])
>>> c.bounding_box.left
0.0
>>> c.bounding_box.lower
0.0
>>> c.bounding_box.right
2.0
>>> c.bounding_box.upper
1.0
"""
if self._bounding_box is None:
vertices = self.vertices
self._bounding_box = Rectangle(
min([v[0] for v in vertices]),
min([v[1] for v in vertices]),
max([v[0] for v in vertices]),
max([v[1] for v in vertices]),
)
return self._bounding_box
@property
def len(self) -> int:
"""Returns the geometric length of the chain.
Examples
--------
>>> c = Chain([Point((0, 0)), Point((1, 0)), Point((1, 1)), Point((2, 1))])
>>> c.len
3.0
>>> c = Chain(
... [
... [Point((0, 0)), Point((1, 0)), Point((1, 1))],
... [Point((10, 10)), Point((11, 10)), Point((11, 11))]
... ]
... )
>>> c.len
4.0
"""
def dist(v1: tuple, v2: tuple) -> int | float:
return math.hypot(v1[0] - v2[0], v1[1] - v2[1])
def part_perimeter(p: list) -> int | float:
return sum([dist(p[i], p[i + 1]) for i in range(len(p) - 1)])
if self._len is None:
self._len = sum([part_perimeter(part) for part in self._vertices])
return self._len
@property
def arclen(self) -> int | float:
"""Returns the geometric length of the chain
computed using 'arcdistance' (meters).
"""
def part_perimeter(p: list) -> int | float:
return sum([arcdist(p[i], p[i + 1]) * 1000.0 for i in range(len(p) - 1)])
if self._arclen is None:
self._arclen = sum([part_perimeter(part) for part in self._vertices])
return self._arclen
@property
def segments(self) -> list:
"""Returns the segments that compose the chain."""
return [
[LineSegment(a, b) for (a, b) in zip(part[:-1], part[1:], strict=True)]
for part in self._vertices
]
class Ring(Geometry):
"""Geometric representation of a linear ring. Linear rings must be
closed, the first and last point must be the same. Open rings will
be closed. This class exists primarily as a geometric primitive to
form complex polygons with multiple rings and holes. The ordering
of the vertices is ignored and will not be altered.
Parameters
----------
vertices : list
A list of vertices.
Attributes
----------
vertices : list
A list of points with the vertices of the ring.
len : int
The number of vertices.
perimeter : float
The geometric length of the perimeter of the ring.
bounding_box : libpysal.cg.Rectangle
The bounding box of the ring.
area : float
The area enclosed by the ring.
centroid : {tuple, libpysal.cg.Point}
The centroid of the ring defined by the 'center of gravity'
or 'center or mass'.
_quad_tree_structure : libpysal.cg.QuadTreeStructureSingleRing
The quad tree structure for the ring. This structure helps
test if a point is inside the ring.
"""
def __init__(self, vertices):
warnings.warn(dep_msg, FutureWarning, stacklevel=2)
if vertices[0] != vertices[-1]:
vertices = vertices[:] + vertices[0:1]
# msg = "Supplied vertices do not form a closed ring, "
# msg += "the first and last vertices are not the same."
# raise ValueError(msg)
self.vertices = tuple(vertices)
self._perimeter = None
self._bounding_box = None
self._area = None
self._centroid = None
self._quad_tree_structure = None
def __len__(self) -> int:
return len(self.vertices)
@property
def len(self) -> int:
return len(self)
@staticmethod
def dist(v1, v2) -> int | float:
return math.hypot(v1[0] - v2[0], v1[1] - v2[1])
@property
def perimeter(self) -> int | float:
if self._perimeter is None:
dist = self.dist
v = self.vertices
self._perimeter = sum(
[dist(v[i], v[i + 1]) for i in range(-1, len(self) - 1)]
)
return self._perimeter
@property
def bounding_box(self):
"""Returns the bounding box of the ring.
Returns
-------
self._bounding_box : libpysal.cg.Rectangle
The bounding box of the ring.
Examples
--------
>>> r = Ring(
... [
... Point((0, 0)),
... Point((2, 0)),
... Point((2, 1)),
... Point((0, 1)),
... Point((0, 0))
... ]
... )
>>> r.bounding_box.left
0.0
>>> r.bounding_box.lower
0.0
>>> r.bounding_box.right
2.0
>>> r.bounding_box.upper
1.0
"""
if self._bounding_box is None:
vertices = self.vertices
x = [v[0] for v in vertices]
y = [v[1] for v in vertices]
self._bounding_box = Rectangle(min(x), min(y), max(x), max(y))
return self._bounding_box
@property
def area(self) -> int | float:
"""Returns the area of the ring.
Examples
--------
>>> r = Ring(
... [
... Point((0, 0)),
... Point((2, 0)),
... Point((2, 1)),
... Point((0, 1)),
... Point((0, 0))
... ]
... )
>>> r.area
2.0
"""
return abs(self.signed_area)
@property
def signed_area(self) -> int | float:
if self._area is None:
vertices = self.vertices
x = [v[0] for v in vertices]
y = [v[1] for v in vertices]
n = len(self)
a = 0.0
for i in range(n - 1):
a += (x[i] + x[i + 1]) * (y[i] - y[i + 1])
a = a * 0.5
self._area = -a
return self._area
@property
def centroid(self):
"""Returns the centroid of the ring.
Returns
-------
self._centroid : libpysal.cg.Point
The ring's centroid.
Notes
-----
The centroid returned by this method is the geometric centroid.
Also known as the 'center of gravity' or 'center of mass'.
Examples
--------
>>> r = Ring(
... [
... Point((0, 0)),
... Point((2, 0)),
... Point((2, 1)),
... Point((0, 1)),
... Point((0, 0))
... ]
... )
>>> str(r.centroid)
'(1.0, 0.5)'
"""
if self._centroid is None:
vertices = self.vertices
x = [v[0] for v in vertices]
y = [v[1] for v in vertices]
a = self.signed_area
n = len(self)
cx = 0
cy = 0
for i in range(n - 1):
f = x[i] * y[i + 1] - x[i + 1] * y[i]
cx += (x[i] + x[i + 1]) * f
cy += (y[i] + y[i + 1]) * f
cx = 1.0 / (6 * a) * cx
cy = 1.0 / (6 * a) * cy
self._centroid = Point((cx, cy))
return self._centroid
def build_quad_tree_structure(self):
"""Build the quad tree structure for this polygon. Once
the structure is built, speed for testing if a point is
inside the ring will be increased significantly.
"""
self._quad_tree_structure = QuadTreeStructureSingleRing(self)
def contains_point(self, point):
"""Point containment using winding number. The implementation is based on
`this <http://www.engr.colostate.edu/~dga/dga/papers/point_in_polygon.pdf>`_.
Parameters
----------
point : libpysal.cg.Point
The point to test for containment.
Returns
-------
point_contained : bool
``True`` if ``point`` is contained within the polygon, otherwise ``False``.
"""
point_contained = False
if self._quad_tree_structure is None:
x, y = point
# bbox checks
bbleft = x < self.bounding_box.left
bbright = x > self.bounding_box.right
bblower = y < self.bounding_box.lower
bbupper = y > self.bounding_box.upper
if bbleft or bbright or bblower or bbupper:
pass
else:
rn = len(self.vertices)
xs = [self.vertices[i][0] - point[0] for i in range(rn)]
ys = [self.vertices[i][1] - point[1] for i in range(rn)]
w = 0
for i in range(len(self.vertices) - 1):
yi = ys[i]
yj = ys[i + 1]
xi = xs[i]
xj = xs[i + 1]
if yi * yj < 0:
r = xi + yi * (xj - xi) / (yi - yj)
if r > 0:
if yi < 0:
w += 1
else:
w -= 1
elif yi == 0 and xi > 0:
if yj > 0:
w += 0.5
else:
w -= 0.5
elif yj == 0 and xj > 0:
if yi < 0:
w += 0.5
else:
w -= 0.5
if w == 0:
pass
else:
point_contained = True
else:
point_contained = self._quad_tree_structure.contains_point(point)
return point_contained
[docs]
class Polygon(Geometry):
"""Geometric representation of polygon objects.
Returns a polygon created from the objects specified.
Parameters
----------
vertices : list
A list of vertices or a list of lists of vertices.
holes : list
A list of sub-polygons to be considered as holes.
Default is ``None``.
Attributes
----------
vertices : list
A list of points with the vertices of the polygon in clockwise order.
len : int
The number of vertices including holes.
perimeter : float
The geometric length of the perimeter of the polygon.
bounding_box : libpysal.cg.Rectangle
The bounding box of the polygon.
bbox : list
A list representation of the bounding box in the
form ``[left, lower, right, upper]``.
area : float
The area enclosed by the polygon.
centroid : tuple
The 'center of gravity', i.e. the mean point of the polygon.
Examples
--------
>>> p1 = Polygon([Point((0, 0)), Point((1, 0)), Point((1, 1)), Point((0, 1))])
"""
[docs]
def __init__(self, vertices, holes=None):
warnings.warn(dep_msg, FutureWarning, stacklevel=2)
self._part_rings = []
self._hole_rings = []
def clockwise(part: list) -> list:
if standalone.is_clockwise(part):
return part[:]
else:
return part[::-1]
vl = list(vertices)
if isinstance(vl[0], list):
self._part_rings = list(map(Ring, vertices))
self._vertices = [clockwise(part) for part in vertices]
else:
self._part_rings = [Ring(vertices)]
self._vertices = [clockwise(vertices)]
if holes is not None and holes != []:
if isinstance(holes[0], list):
self._hole_rings = list(map(Ring, holes))
self._holes = [clockwise(hole) for hole in holes]
else:
self._hole_rings = [Ring(holes)]
self._holes = [clockwise(holes)]
else:
self._holes = [[]]
self._reset_props()
@classmethod
def __from_geo_interface__(cls, geo: dict):
"""While PySAL does not differentiate polygons and multipolygons
GEOS, Shapely, and geoJSON do. In GEOS, etc, polygons may only
have a single exterior ring, all other parts are holes.
MultiPolygons are simply a list of polygons.
"""
geo_type = geo["type"].lower()
if geo_type == "multipolygon":
parts = []
holes = []
for polygon in geo["coordinates"]:
verts = [[Point(pt) for pt in part] for part in polygon]
parts += verts[0:1]
holes += verts[1:]
if not holes:
holes = None
return cls(parts, holes)
else:
verts = [[Point(pt) for pt in part] for part in geo["coordinates"]]
return cls(verts[0:1], verts[1:])
@property
def __geo_interface__(self) -> dict:
"""Return ``__geo_interface__`` information lookup."""
if len(self.parts) > 1:
geo = {
"type": "MultiPolygon",
"coordinates": [[part] for part in self.parts],
}
if self._holes[0]:
geo["coordinates"][0] += self._holes
return geo
if self._holes[0]:
return {"type": "Polygon", "coordinates": self._vertices + self._holes}
else:
return {"type": "Polygon", "coordinates": self._vertices}
def _reset_props(self):
"""Resets the geometric properties of the polygon."""
self._perimeter = None
self._bounding_box = None
self._bbox = None
self._area = None
self._centroid = None
self._len = None
def __len__(self) -> int:
return self.len
@property
def len(self) -> int:
"""Returns the number of vertices in the polygon.
Examples
--------
>>> p1 = Polygon([Point((0, 0)), Point((0, 1)), Point((1, 1)), Point((1, 0))])
>>> p1.len
4
>>> len(p1)
4
"""
if self._len is None:
self._len = len(self.vertices)
return self._len
@property
def vertices(self) -> list:
"""Returns the vertices of the polygon in clockwise order.
Examples
--------
>>> p1 = Polygon([Point((0, 0)), Point((0, 1)), Point((1, 1)), Point((1, 0))])
>>> len(p1.vertices)
4
"""
return sum(list(self._vertices), []) + sum(list(self._holes), [])
@property
def holes(self) -> list:
"""Returns the holes of the polygon in clockwise order.
Examples
--------
>>> p = Polygon(
... [Point((0, 0)), Point((10, 0)), Point((10, 10)), Point((0, 10))],
... [Point((1, 2)), Point((2, 2)), Point((2, 1)), Point((1, 1))]
... )
>>> len(p.holes)
1
"""
return [list(part) for part in self._holes]
@property
def parts(self) -> list:
"""Returns the parts of the polygon in clockwise order.
Examples
--------
>>> p = Polygon(
... [
... [Point((0, 0)), Point((1, 0)), Point((1, 1)), Point((0, 1))],
... [Point((2, 1)), Point((2, 2)), Point((1, 2)), Point((1, 1))]
... ]
... )
>>> len(p.parts)
2
"""
return [list(part) for part in self._vertices]
@property
def perimeter(self) -> int | float:
"""Returns the perimeter of the polygon.
Examples
--------
>>> p = Polygon([Point((0, 0)), Point((1, 0)), Point((1, 1)), Point((0, 1))])
>>> p.perimeter
4.0
"""
def dist(v1: int | float, v2: int | float) -> float:
return math.hypot(v1[0] - v2[0], v1[1] - v2[1])
def part_perimeter(part) -> int | float:
return sum([dist(part[i], part[i + 1]) for i in range(-1, len(part) - 1)])
sum_perim = lambda part_type: sum( # noqa: E731
[part_perimeter(part) for part in part_type]
)
if self._perimeter is None:
self._perimeter = sum_perim(self._vertices) + sum_perim(self._holes)
return self._perimeter
@property
def bbox(self):
"""Returns the bounding box of the polygon as a list.
Returns
-------
self._bbox : list
The bounding box of the polygon as a list.
See Also
--------
libpysal.cg.bounding_box
"""
if self._bbox is None:
self._bbox = [
self.bounding_box.left,
self.bounding_box.lower,
self.bounding_box.right,
self.bounding_box.upper,
]
return self._bbox
@property
def bounding_box(self):
"""Returns the bounding box of the polygon.
Returns
-------
self._bounding_box : libpysal.cg.Rectangle
The bounding box of the polygon.
Examples
--------
>>> p = Polygon([Point((0, 0)), Point((2, 0)), Point((2, 1)), Point((0, 1))])
>>> p.bounding_box.left
0.0
>>> p.bounding_box.lower
0.0
>>> p.bounding_box.right
2.0
>>> p.bounding_box.upper
1.0
"""
if self._bounding_box is None:
vertices = self.vertices
self._bounding_box = Rectangle(
min([v[0] for v in vertices]),
min([v[1] for v in vertices]),
max([v[0] for v in vertices]),
max([v[1] for v in vertices]),
)
return self._bounding_box
@property
def area(self) -> float:
"""Returns the area of the polygon.
Examples
--------
>>> p = Polygon([Point((0, 0)), Point((1, 0)), Point((1, 1)), Point((0, 1))])
>>> p.area
1.0
>>> p = Polygon(
... [Point((0, 0)), Point((10, 0)), Point((10, 10)), Point((0, 10))],
... [Point((2, 1)), Point((2, 2)), Point((1, 2)), Point((1, 1))]
... )
>>> p.area
99.0
"""
def part_area(pv: list) -> float:
__area = 0
for i in range(-1, len(pv) - 1):
__area += (pv[i][0] + pv[i + 1][0]) * (pv[i][1] - pv[i + 1][1])
__area = __area * 0.5
if __area < 0:
__area = -area # noqa: F821
return __area
sum_area = lambda part_type: sum( # noqa: E731
[part_area(part) for part in part_type]
)
_area = sum_area(self._vertices) - sum_area(self._holes)
return _area
@property
def centroid(self) -> tuple:
"""Returns the centroid of the polygon.
Notes
-----
The centroid returned by this method is the geometric
centroid and respects multipart polygons with holes.
Also known as the 'center of gravity' or 'center of mass'.
Examples
--------
>>> p = Polygon(
... [Point((0, 0)), Point((10, 0)), Point((10, 10)), Point((0, 10))],
... [Point((1, 1)), Point((1, 2)), Point((2, 2)), Point((2, 1))]
... )
>>> p.centroid
(5.0353535353535355, 5.0353535353535355)
"""
cp = [ring.centroid for ring in self._part_rings]
ap = [ring.area for ring in self._part_rings]
ch = [ring.centroid for ring in self._hole_rings]
ah = [-ring.area for ring in self._hole_rings]
a = ap + ah
cx = sum([pt[0] * area for pt, area in zip(cp + ch, a, strict=True)]) / sum(a)
cy = sum([pt[1] * area for pt, area in zip(cp + ch, a, strict=True)]) / sum(a)
return cx, cy
[docs]
def build_quad_tree_structure(self):
"""Build the quad tree structure for this polygon. Once
the structure is built, speed for testing if a point is
inside the ring will be increased significantly.
"""
for ring in self._part_rings:
ring.build_quad_tree_structure()
for ring in self._hole_rings:
ring.build_quad_tree_structure()
self.is_quad_tree_structure_built = True
[docs]
def contains_point(self, point):
"""Test if a polygon contains a point.
Parameters
----------
point : libpysal.cg.Point
A point to test for containment.
Returns
-------
contains : bool
``True`` if the polygon contains ``point`` otherwise ``False``.
Examples
--------
>>> p = Polygon(
... [Point((0,0)), Point((4,0)), Point((4,5)), Point((2,3)), Point((0,5))]
... )
>>> p.contains_point((3,3))
1
>>> p.contains_point((0,6))
0
>>> p.contains_point((2,2.9))
1
>>> p.contains_point((4,5))
0
>>> p.contains_point((4,0))
0
Handles holes.
>>> p = Polygon(
... [Point((0, 0)), Point((0, 10)), Point((10, 10)), Point((10, 0))],
... [Point((2, 2)), Point((4, 2)), Point((4, 4)), Point((2, 4))]
... )
>>> p.contains_point((3.0, 3.0))
False
>>> p.contains_point((1.0, 1.0))
True
Notes
-----
Points falling exactly on polygon edges may yield unpredictable results.
"""
searching = True
for ring in self._hole_rings:
if ring.contains_point(point):
contains = False
searching = False
break
if searching:
for ring in self._part_rings:
if ring.contains_point(point):
contains = True
searching = False
break
if searching:
contains = False
return contains
[docs]
class Rectangle(Geometry):
"""Geometric representation of rectangle objects.
Attributes
----------
left : float
Minimum x-value of the rectangle.
lower : float
Minimum y-value of the rectangle.
right : float
Maximum x-value of the rectangle.
upper : float
Maximum y-value of the rectangle.
Examples
--------
>>> r = Rectangle(-4, 3, 10, 17)
>>> r.left #minx
-4.0
>>> r.lower #miny
3.0
>>> r.right #maxx
10.0
>>> r.upper #maxy
17.0
"""
[docs]
def __init__(self, left, lower, right, upper):
warnings.warn(dep_msg, FutureWarning, stacklevel=2)
if right < left or upper < lower:
raise ArithmeticError("Rectangle must have positive area.")
self.left = float(left)
self.lower = float(lower)
self.right = float(right)
self.upper = float(upper)
def __bool__(self):
"""Rectangles will evaluate to False if they have zero area.
``___nonzero__`` is used "to implement truth value
testing and the built-in operation ``bool()``"
``-- http://docs.python.org/reference/datamodel.html
Examples
--------
>>> r = Rectangle(0, 0, 0, 0)
>>> bool(r)
False
>>> r = Rectangle(0, 0, 1, 1)
>>> bool(r)
True
"""
return bool(self.area)
def __eq__(self, other):
if other:
return self[:] == other[:]
return False
def __add__(self, other):
x, y, X, Y = self[:] # noqa: N806
x1, y2, X1, Y1 = other[:] # noqa: N806
return Rectangle(
min(self.left, other.left),
min(self.lower, other.lower),
max(self.right, other.right),
max(self.upper, other.upper),
)
def __getitem__(self, key):
"""
Examples
--------
>>> r = Rectangle(-4, 3, 10, 17)
>>> r[:]
[-4.0, 3.0, 10.0, 17.0]
"""
l_ = [self.left, self.lower, self.right, self.upper]
return l_.__getitem__(key)
[docs]
def set_centroid(self, new_center):
"""Moves the rectangle center to a new specified point.
Parameters
----------
new_center : libpysal.cg.Point
The new location of the centroid of the polygon.
Examples
--------
>>> r = Rectangle(0, 0, 4, 4)
>>> r.set_centroid(Point((4, 4)))
>>> r.left
2.0
>>> r.right
6.0
>>> r.lower
2.0
>>> r.upper
6.0
"""
shift = (
new_center[0] - (self.left + self.right) / 2,
new_center[1] - (self.lower + self.upper) / 2,
)
self.left = self.left + shift[0]
self.right = self.right + shift[0]
self.lower = self.lower + shift[1]
self.upper = self.upper + shift[1]
[docs]
def set_scale(self, scale):
"""Rescales the rectangle around its center.
Parameters
----------
scale : int, float
The ratio of the new scale to the old
scale (e.g. 1.0 is current size).
Examples
--------
>>> r = Rectangle(0, 0, 4, 4)
>>> r.set_scale(2)
>>> r.left
-2.0
>>> r.right
6.0
>>> r.lower
-2.0
>>> r.upper
6.0
"""
center = ((self.left + self.right) / 2, (self.lower + self.upper) / 2)
self.left = center[0] + scale * (self.left - center[0])
self.right = center[0] + scale * (self.right - center[0])
self.lower = center[1] + scale * (self.lower - center[1])
self.upper = center[1] + scale * (self.upper - center[1])
@property
def area(self) -> int | float:
"""Returns the area of the Rectangle.
Examples
--------
>>> r = Rectangle(0, 0, 4, 4)
>>> r.area
16.0
"""
return (self.right - self.left) * (self.upper - self.lower)
@property
def width(self) -> int | float:
"""Returns the width of the Rectangle.
Examples
--------
>>> r = Rectangle(0, 0, 4, 4)
>>> r.width
4.0
"""
return self.right - self.left
@property
def height(self) -> int | float:
"""Returns the height of the Rectangle.
Examples
--------
>>> r = Rectangle(0, 0, 4, 4)
>>> r.height
4.0
"""
return self.upper - self.lower
_geoJSON_type_to_Pysal_type = { # noqa: N816
"point": Point,
"linestring": Chain,
"multilinestring": Chain,
"polygon": Polygon,
"multipolygon": Polygon,
}
# moving this to top breaks unit tests !
from . import standalone
from .polygonQuadTreeStructure import QuadTreeStructureSingleRing