2018-10-03 18:59:01 +00:00
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# setup: import numpy as np ; N = 50 ; X, Y = np.random.randn(100,N), np.random.randn(40,N) # noqa
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# run: allpairs_distances(X, Y)
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2018-04-05 22:07:33 +00:00
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2018-10-03 18:59:01 +00:00
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# pythran export allpairs_distances(float64[][], float64[][])
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2018-04-05 22:07:33 +00:00
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import numpy as np
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2018-10-03 12:38:48 +00:00
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def allpairs_distances(A, B):
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""" This returns the euclidean distances squared
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dist2(x, y) = dot(x, x) - 2 * dot(x, y) + dot(y, y)
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"""
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A2 = np.einsum('ij,ij->i', A, A)
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B2 = np.einsum('ij,ij->i', B, B)
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2018-10-03 18:59:01 +00:00
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return A2[:, None] + B2[None, :] - 2 * np.dot(A, B.T)
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