116 lines
5.2 KiB
Python
116 lines
5.2 KiB
Python
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from __future__ import division, absolute_import, print_function
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import numpy as np
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from numpy.testing import (assert_almost_equal,
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assert_array_equal,
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assert_equal,
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assert_)
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from scipy.spatial.distance import directed_hausdorff
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from scipy.spatial import distance
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from scipy._lib._util import check_random_state
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class TestHausdorff(object):
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# Test various properties of the directed Hausdorff code.
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def setup_method(self):
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np.random.seed(1234)
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random_angles = np.random.random(100) * np.pi * 2
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random_columns = np.column_stack(
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(random_angles, random_angles, np.zeros(100)))
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random_columns[..., 0] = np.cos(random_columns[..., 0])
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random_columns[..., 1] = np.sin(random_columns[..., 1])
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random_columns_2 = np.column_stack(
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(random_angles, random_angles, np.zeros(100)))
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random_columns_2[1:, 0] = np.cos(random_columns_2[1:, 0]) * 2.0
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random_columns_2[1:, 1] = np.sin(random_columns_2[1:, 1]) * 2.0
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# move one point farther out so we don't have two perfect circles
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random_columns_2[0, 0] = np.cos(random_columns_2[0, 0]) * 3.3
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random_columns_2[0, 1] = np.sin(random_columns_2[0, 1]) * 3.3
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self.path_1 = random_columns
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self.path_2 = random_columns_2
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self.path_1_4d = np.insert(self.path_1, 3, 5, axis=1)
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self.path_2_4d = np.insert(self.path_2, 3, 27, axis=1)
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def test_symmetry(self):
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# Ensure that the directed (asymmetric) Hausdorff distance is
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# actually asymmetric
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forward = directed_hausdorff(self.path_1, self.path_2)[0]
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reverse = directed_hausdorff(self.path_2, self.path_1)[0]
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assert_(forward != reverse)
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def test_brute_force_comparison_forward(self):
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# Ensure that the algorithm for directed_hausdorff gives the
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# same result as the simple / brute force approach in the
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# forward direction.
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actual = directed_hausdorff(self.path_1, self.path_2)[0]
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# brute force over rows:
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expected = max(np.amin(distance.cdist(self.path_1, self.path_2),
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axis=1))
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assert_almost_equal(actual, expected, decimal=9)
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def test_brute_force_comparison_reverse(self):
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# Ensure that the algorithm for directed_hausdorff gives the
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# same result as the simple / brute force approach in the
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# reverse direction.
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actual = directed_hausdorff(self.path_2, self.path_1)[0]
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# brute force over columns:
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expected = max(np.amin(distance.cdist(self.path_1, self.path_2),
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axis=0))
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assert_almost_equal(actual, expected, decimal=9)
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def test_degenerate_case(self):
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# The directed Hausdorff distance must be zero if both input
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# data arrays match.
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actual = directed_hausdorff(self.path_1, self.path_1)[0]
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assert_almost_equal(actual, 0.0, decimal=9)
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def test_2d_data_forward(self):
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# Ensure that 2D data is handled properly for a simple case
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# relative to brute force approach.
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actual = directed_hausdorff(self.path_1[..., :2],
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self.path_2[..., :2])[0]
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expected = max(np.amin(distance.cdist(self.path_1[..., :2],
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self.path_2[..., :2]),
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axis=1))
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assert_almost_equal(actual, expected, decimal=9)
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def test_4d_data_reverse(self):
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# Ensure that 4D data is handled properly for a simple case
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# relative to brute force approach.
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actual = directed_hausdorff(self.path_2_4d, self.path_1_4d)[0]
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# brute force over columns:
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expected = max(np.amin(distance.cdist(self.path_1_4d, self.path_2_4d),
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axis=0))
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assert_almost_equal(actual, expected, decimal=9)
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def test_indices(self):
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# Ensure that correct point indices are returned -- they should
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# correspond to the Hausdorff pair
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path_simple_1 = np.array([[-1,-12],[0,0], [1,1], [3,7], [1,2]])
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path_simple_2 = np.array([[0,0], [1,1], [4,100], [10,9]])
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actual = directed_hausdorff(path_simple_2, path_simple_1)[1:]
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expected = (2, 3)
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assert_array_equal(actual, expected)
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def test_random_state(self):
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# ensure that the global random state is not modified because
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# the directed Hausdorff algorithm uses randomization
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rs = check_random_state(None)
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old_global_state = rs.get_state()
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directed_hausdorff(self.path_1, self.path_2)
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rs2 = check_random_state(None)
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new_global_state = rs2.get_state()
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assert_equal(new_global_state, old_global_state)
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def test_random_state_None_int(self):
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# check that seed values of None or int do not alter global
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# random state
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for seed in [None, 27870671]:
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rs = check_random_state(None)
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old_global_state = rs.get_state()
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directed_hausdorff(self.path_1, self.path_2, seed)
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rs2 = check_random_state(None)
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new_global_state = rs2.get_state()
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assert_equal(new_global_state, old_global_state)
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