81 lines
3.0 KiB
Python
81 lines
3.0 KiB
Python
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import numpy as np
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import pytest
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from scipy.sparse.csgraph import connected_components
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from sklearn.metrics.pairwise import pairwise_distances
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from sklearn.neighbors import kneighbors_graph
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from sklearn.utils.graph import _fix_connected_components
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def test_fix_connected_components():
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# Test that _fix_connected_components reduces the number of component to 1.
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X = np.array([0, 1, 2, 5, 6, 7])[:, None]
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graph = kneighbors_graph(X, n_neighbors=2, mode="distance")
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n_connected_components, labels = connected_components(graph)
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assert n_connected_components > 1
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graph = _fix_connected_components(X, graph, n_connected_components, labels)
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n_connected_components, labels = connected_components(graph)
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assert n_connected_components == 1
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def test_fix_connected_components_precomputed():
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# Test that _fix_connected_components accepts precomputed distance matrix.
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X = np.array([0, 1, 2, 5, 6, 7])[:, None]
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graph = kneighbors_graph(X, n_neighbors=2, mode="distance")
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n_connected_components, labels = connected_components(graph)
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assert n_connected_components > 1
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distances = pairwise_distances(X)
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graph = _fix_connected_components(
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distances, graph, n_connected_components, labels, metric="precomputed"
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)
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n_connected_components, labels = connected_components(graph)
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assert n_connected_components == 1
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# but it does not work with precomputed neighbors graph
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with pytest.raises(RuntimeError, match="does not work with a sparse"):
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_fix_connected_components(
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graph, graph, n_connected_components, labels, metric="precomputed"
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)
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def test_fix_connected_components_wrong_mode():
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# Test that the an error is raised if the mode string is incorrect.
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X = np.array([0, 1, 2, 5, 6, 7])[:, None]
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graph = kneighbors_graph(X, n_neighbors=2, mode="distance")
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n_connected_components, labels = connected_components(graph)
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with pytest.raises(ValueError, match="Unknown mode"):
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graph = _fix_connected_components(
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X, graph, n_connected_components, labels, mode="foo"
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)
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def test_fix_connected_components_connectivity_mode():
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# Test that the connectivity mode fill new connections with ones.
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X = np.array([0, 1, 6, 7])[:, None]
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graph = kneighbors_graph(X, n_neighbors=1, mode="connectivity")
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n_connected_components, labels = connected_components(graph)
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graph = _fix_connected_components(
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X, graph, n_connected_components, labels, mode="connectivity"
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)
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assert np.all(graph.data == 1)
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def test_fix_connected_components_distance_mode():
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# Test that the distance mode does not fill new connections with ones.
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X = np.array([0, 1, 6, 7])[:, None]
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graph = kneighbors_graph(X, n_neighbors=1, mode="distance")
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assert np.all(graph.data == 1)
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n_connected_components, labels = connected_components(graph)
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graph = _fix_connected_components(
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X, graph, n_connected_components, labels, mode="distance"
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)
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assert not np.all(graph.data == 1)
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