import numpy as np from numpy.testing import assert_equal, assert_array_almost_equal from scipy.sparse import csgraph def test_weak_connections(): Xde = np.array([[0, 1, 0], [0, 0, 0], [0, 0, 0]]) Xsp = csgraph.csgraph_from_dense(Xde, null_value=0) for X in Xsp, Xde: n_components, labels =\ csgraph.connected_components(X, directed=True, connection='weak') assert_equal(n_components, 2) assert_array_almost_equal(labels, [0, 0, 1]) def test_strong_connections(): X1de = np.array([[0, 1, 0], [0, 0, 0], [0, 0, 0]]) X2de = X1de + X1de.T X1sp = csgraph.csgraph_from_dense(X1de, null_value=0) X2sp = csgraph.csgraph_from_dense(X2de, null_value=0) for X in X1sp, X1de: n_components, labels =\ csgraph.connected_components(X, directed=True, connection='strong') assert_equal(n_components, 3) labels.sort() assert_array_almost_equal(labels, [0, 1, 2]) for X in X2sp, X2de: n_components, labels =\ csgraph.connected_components(X, directed=True, connection='strong') assert_equal(n_components, 2) labels.sort() assert_array_almost_equal(labels, [0, 0, 1]) def test_strong_connections2(): X = np.array([[0, 0, 0, 0, 0, 0], [1, 0, 1, 0, 0, 0], [0, 0, 0, 1, 0, 0], [0, 0, 1, 0, 1, 0], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 1, 0]]) n_components, labels =\ csgraph.connected_components(X, directed=True, connection='strong') assert_equal(n_components, 5) labels.sort() assert_array_almost_equal(labels, [0, 1, 2, 2, 3, 4]) def test_weak_connections2(): X = np.array([[0, 0, 0, 0, 0, 0], [1, 0, 0, 0, 0, 0], [0, 0, 0, 1, 0, 0], [0, 0, 1, 0, 1, 0], [0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 1, 0]]) n_components, labels =\ csgraph.connected_components(X, directed=True, connection='weak') assert_equal(n_components, 2) labels.sort() assert_array_almost_equal(labels, [0, 0, 1, 1, 1, 1]) def test_ticket1876(): # Regression test: this failed in the original implementation # There should be two strongly-connected components; previously gave one g = np.array([[0, 1, 1, 0], [1, 0, 0, 1], [0, 0, 0, 1], [0, 0, 1, 0]]) n_components, labels = csgraph.connected_components(g, connection='strong') assert_equal(n_components, 2) assert_equal(labels[0], labels[1]) assert_equal(labels[2], labels[3]) def test_fully_connected_graph(): # Fully connected dense matrices raised an exception. # https://github.com/scipy/scipy/issues/3818 g = np.ones((4, 4)) n_components, labels = csgraph.connected_components(g) assert_equal(n_components, 1)