31 lines
942 B
Python
31 lines
942 B
Python
# Authors: Gael Varoquaux <gael.varoquaux@normalesup.org>
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# Justin Vincent
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# Lars Buitinck
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# License: BSD 3 clause
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import numpy as np
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from nose.tools import assert_equal
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from numpy.testing import (assert_almost_equal,
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assert_array_almost_equal)
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from ..fixes import divide, expit
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def test_expit():
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"""Check numerical stability of expit (logistic function)."""
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# Simulate our previous Cython implementation, based on
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#http://fa.bianp.net/blog/2013/numerical-optimizers-for-logistic-regression
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assert_almost_equal(expit(1000.), 1. / (1. + np.exp(-1000.)), decimal=16)
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assert_almost_equal(expit(-1000.), np.exp(-1000.) / (1. + np.exp(-1000.)),
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decimal=16)
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x = np.arange(10)
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out = np.zeros_like(x, dtype=np.float32)
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assert_array_almost_equal(expit(x), expit(x, out=out))
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def test_divide():
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assert_equal(divide(.6, 1), .600000000000)
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