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import unittest
import pytest
from shapely.errors import GeometryTypeError
from shapely.geometry import (
LineString,
MultiLineString,
MultiPoint,
MultiPolygon,
Point,
Polygon,
)
from shapely.ops import linemerge, split, unary_union
class TestSplitGeometry(unittest.TestCase):
# helper class for testing below
def helper(self, geom, splitter, expected_chunks):
s = split(geom, splitter)
assert s.geom_type == "GeometryCollection"
assert len(s.geoms) == expected_chunks
if expected_chunks > 1:
# split --> expected collection that when merged is again equal to original
# geometry
if s.geoms[0].geom_type == "LineString":
self.assertTrue(linemerge(s).simplify(0.000001).equals(geom))
elif s.geoms[0].geom_type == "Polygon":
union = unary_union(s).simplify(0.000001)
assert union.equals(geom)
assert union.area == geom.area
else:
raise ValueError
elif expected_chunks == 1:
# not split --> expected equal to line
assert s.geoms[0].equals(geom)
def test_split_closed_line_with_point(self):
# point at start/end of closed ring -> return equal
# see GH #524
ls = LineString([(0, 0), (0, 1), (1, 1), (1, 0), (0, 0)])
splitter = Point(0, 0)
self.helper(ls, splitter, 1)
class TestSplitPolygon(TestSplitGeometry):
poly_simple = Polygon([(0, 0), (2, 0), (2, 2), (0, 2), (0, 0)])
poly_hole = Polygon(
[(0, 0), (2, 0), (2, 2), (0, 2), (0, 0)],
[[(0.5, 0.5), (0.5, 1.5), (1.5, 1.5), (1.5, 0.5), (0.5, 0.5)]],
)
def test_split_poly_with_line(self):
# crossing at 2 points --> return 2 polygons
splitter = LineString([(1, 3), (1, -3)])
self.helper(self.poly_simple, splitter, 2)
self.helper(self.poly_hole, splitter, 2)
# crossing twice with one linestring --> return 3 polygons
splitter = LineString([(1, 3), (1, -3), (1.7, -3), (1.7, 3)])
self.helper(self.poly_simple, splitter, 3)
self.helper(self.poly_hole, splitter, 3)
# touching the boundary --> return equal
splitter = LineString([(0, 2), (5, 2)])
self.helper(self.poly_simple, splitter, 1)
self.helper(self.poly_hole, splitter, 1)
# inside the polygon --> return equal
splitter = LineString([(0.2, 0.2), (1.7, 1.7), (3, 2)])
self.helper(self.poly_simple, splitter, 1)
self.helper(self.poly_hole, splitter, 1)
# outside the polygon --> return equal
splitter = LineString([(0, 3), (3, 3), (3, 0)])
self.helper(self.poly_simple, splitter, 1)
self.helper(self.poly_hole, splitter, 1)
def test_split_poly_with_multiline(self):
# crossing twice with a multilinestring --> return 3 polygons
splitter = MultiLineString([[(0.2, 3), (0.2, -3)], [(1.7, -3), (1.7, 3)]])
self.helper(self.poly_simple, splitter, 3)
self.helper(self.poly_hole, splitter, 3)
# crossing twice with a cross multilinestring --> return 4 polygons
splitter = MultiLineString([[(0.2, 3), (0.2, -3)], [(-3, 1), (3, 1)]])
self.helper(self.poly_simple, splitter, 4)
self.helper(self.poly_hole, splitter, 4)
# cross once, touch the boundary once --> return 2 polygons
splitter = MultiLineString([[(0.2, 3), (0.2, -3)], [(0, 2), (5, 2)]])
self.helper(self.poly_simple, splitter, 2)
self.helper(self.poly_hole, splitter, 2)
# cross once, inside the polygon once --> return 2 polygons
splitter = MultiLineString(
[[(0.2, 3), (0.2, -3)], [(1.2, 1.2), (1.7, 1.7), (3, 2)]]
)
self.helper(self.poly_simple, splitter, 2)
self.helper(self.poly_hole, splitter, 2)
# cross once, outside the polygon once --> return 2 polygons
splitter = MultiLineString([[(0.2, 3), (0.2, -3)], [(0, 3), (3, 3), (3, 0)]])
self.helper(self.poly_simple, splitter, 2)
self.helper(self.poly_hole, splitter, 2)
def test_split_poly_with_other(self):
with pytest.raises(GeometryTypeError):
split(self.poly_simple, Point(1, 1))
with pytest.raises(GeometryTypeError):
split(self.poly_simple, MultiPoint([(1, 1), (3, 4)]))
with pytest.raises(GeometryTypeError):
split(self.poly_simple, self.poly_hole)
class TestSplitLine(TestSplitGeometry):
ls = LineString([(0, 0), (1.5, 1.5), (3.0, 4.0)])
def test_split_line_with_point(self):
# point on line interior --> return 2 segments
splitter = Point(1, 1)
self.helper(self.ls, splitter, 2)
# point on line point --> return 2 segments
splitter = Point(1.5, 1.5)
self.helper(self.ls, splitter, 2)
# point on boundary --> return equal
splitter = Point(3, 4)
self.helper(self.ls, splitter, 1)
# point on exterior of line --> return equal
splitter = Point(2, 2)
self.helper(self.ls, splitter, 1)
def test_split_line_with_multipoint(self):
# points on line interior --> return 4 segments
splitter = MultiPoint([(1, 1), (1.5, 1.5), (0.5, 0.5)])
self.helper(self.ls, splitter, 4)
# points on line interior and boundary -> return 2 segments
splitter = MultiPoint([(1, 1), (3, 4)])
self.helper(self.ls, splitter, 2)
# point on linear interior but twice --> return 2 segments
splitter = MultiPoint([(1, 1), (1.5, 1.5), (1, 1)])
self.helper(self.ls, splitter, 3)
def test_split_line_with_line(self):
# crosses at one point --> return 2 segments
splitter = LineString([(0, 1), (1, 0)])
self.helper(self.ls, splitter, 2)
# crosses at two points --> return 3 segments
splitter = LineString([(0, 1), (1, 0), (1, 2)])
self.helper(self.ls, splitter, 3)
# overlaps --> raise
splitter = LineString([(0, 0), (15, 15)])
with pytest.raises(ValueError):
self.helper(self.ls, splitter, 1)
# does not cross --> return equal
splitter = LineString([(0, 1), (0, 2)])
self.helper(self.ls, splitter, 1)
# is touching the boundary --> return equal
splitter = LineString([(-1, 1), (1, -1)])
assert splitter.touches(self.ls)
self.helper(self.ls, splitter, 1)
# splitter boundary touches interior of line --> return 2 segments
splitter = LineString([(0, 1), (1, 1)]) # touches at (1, 1)
assert splitter.touches(self.ls)
self.helper(self.ls, splitter, 2)
def test_split_line_with_multiline(self):
# crosses at one point --> return 2 segments
splitter = MultiLineString([[(0, 1), (1, 0)], [(0, 0), (2, -2)]])
self.helper(self.ls, splitter, 2)
# crosses at two points --> return 3 segments
splitter = MultiLineString([[(0, 1), (1, 0)], [(0, 2), (2, 0)]])
self.helper(self.ls, splitter, 3)
# crosses at three points --> return 4 segments
splitter = MultiLineString([[(0, 1), (1, 0)], [(0, 2), (2, 0), (2.2, 3.2)]])
self.helper(self.ls, splitter, 4)
# overlaps --> raise
splitter = MultiLineString([[(0, 0), (1.5, 1.5)], [(1.5, 1.5), (3, 4)]])
with pytest.raises(ValueError):
self.helper(self.ls, splitter, 1)
# does not cross --> return equal
splitter = MultiLineString([[(0, 1), (0, 2)], [(1, 0), (2, 0)]])
self.helper(self.ls, splitter, 1)
def test_split_line_with_polygon(self):
# crosses at two points --> return 3 segments
splitter = Polygon([(1, 0), (1, 2), (2, 2), (2, 0), (1, 0)])
self.helper(self.ls, splitter, 3)
# crosses at one point and touches boundary --> return 2 segments
splitter = Polygon([(0, 0), (1, 2), (2, 2), (1, 0), (0, 0)])
self.helper(self.ls, splitter, 2)
# exterior crosses at one point and touches at (0, 0)
# interior crosses at two points
splitter = Polygon(
[(0, 0), (2, 0), (2, 2), (0, 2), (0, 0)],
[[(0.5, 0.5), (0.5, 1.5), (1.5, 1.5), (1.5, 0.5), (0.5, 0.5)]],
)
self.helper(self.ls, splitter, 4)
def test_split_line_with_multipolygon(self):
poly1 = Polygon(
[(0, 0), (2, 0), (2, 2), (0, 2), (0, 0)]
) # crosses at one point and touches at (0, 0)
poly2 = Polygon(
[(0.5, 0.5), (0.5, 1.5), (1.5, 1.5), (1.5, 0.5), (0.5, 0.5)]
) # crosses at two points
poly3 = Polygon([(0, 0), (0, -2), (-2, -2), (-2, 0), (0, 0)]) # not crossing
splitter = MultiPolygon([poly1, poly2, poly3])
self.helper(self.ls, splitter, 4)
class TestSplitClosedRing(TestSplitGeometry):
ls = LineString([[0, 0], [0, 1], [1, 1], [1, 0], [0, 0]])
def test_split_closed_ring_with_point(self):
splitter = Point([0.0, 0.0])
self.helper(self.ls, splitter, 1)
splitter = Point([0.0, 0.5])
self.helper(self.ls, splitter, 2)
result = split(self.ls, splitter)
assert result.geoms[0].coords[:] == [(0, 0), (0.0, 0.5)]
assert result.geoms[1].coords[:] == [(0.0, 0.5), (0, 1), (1, 1), (1, 0), (0, 0)]
# previously failed, see GH#585
splitter = Point([0.5, 0.0])
self.helper(self.ls, splitter, 2)
result = split(self.ls, splitter)
assert result.geoms[0].coords[:] == [(0, 0), (0, 1), (1, 1), (1, 0), (0.5, 0)]
assert result.geoms[1].coords[:] == [(0.5, 0), (0, 0)]
splitter = Point([2.0, 2.0])
self.helper(self.ls, splitter, 1)
class TestSplitMulti(TestSplitGeometry):
def test_split_multiline_with_point(self):
# a cross-like multilinestring with a point in the middle --> return 4 line
# segments
l1 = LineString([(0, 1), (2, 1)])
l2 = LineString([(1, 0), (1, 2)])
ml = MultiLineString([l1, l2])
splitter = Point((1, 1))
self.helper(ml, splitter, 4)
def test_split_multiline_with_multipoint(self):
# a cross-like multilinestring with a point in middle, a point on one of the
# lines and a point in the exterior
# --> return 4+1 line segments
l1 = LineString([(0, 1), (3, 1)])
l2 = LineString([(1, 0), (1, 2)])
ml = MultiLineString([l1, l2])
splitter = MultiPoint([(1, 1), (2, 1), (4, 2)])
self.helper(ml, splitter, 5)
def test_split_multipolygon_with_line(self):
# two polygons with a crossing line --> return 4 triangles
poly1 = Polygon([(0, 0), (1, 0), (1, 1), (0, 1), (0, 0)])
poly2 = Polygon([(1, 1), (1, 2), (2, 2), (2, 1), (1, 1)])
mpoly = MultiPolygon([poly1, poly2])
ls = LineString([(-1, -1), (3, 3)])
self.helper(mpoly, ls, 4)
# two polygons away from the crossing line --> return identity
poly1 = Polygon([(10, 10), (10, 11), (11, 11), (11, 10), (10, 10)])
poly2 = Polygon([(-10, -10), (-10, -11), (-11, -11), (-11, -10), (-10, -10)])
mpoly = MultiPolygon([poly1, poly2])
ls = LineString([(-1, -1), (3, 3)])
self.helper(mpoly, ls, 2)
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