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# Author: Olivier Grisel <olivier.grisel@ensta.org>
#
# License: BSD 3 clause
import numpy as np
from sklearn.externals.six import b, u
from sklearn.utils.murmurhash import murmurhash3_32
from numpy.testing import assert_array_almost_equal
from numpy.testing import assert_array_equal
from sklearn.utils.testing import assert_equal, assert_true
def test_mmhash3_int():
assert_equal(murmurhash3_32(3), 847579505)
assert_equal(murmurhash3_32(3, seed=0), 847579505)
assert_equal(murmurhash3_32(3, seed=42), -1823081949)
assert_equal(murmurhash3_32(3, positive=False), 847579505)
assert_equal(murmurhash3_32(3, seed=0, positive=False), 847579505)
assert_equal(murmurhash3_32(3, seed=42, positive=False), -1823081949)
assert_equal(murmurhash3_32(3, positive=True), 847579505)
assert_equal(murmurhash3_32(3, seed=0, positive=True), 847579505)
assert_equal(murmurhash3_32(3, seed=42, positive=True), 2471885347)
def test_mmhash3_int_array():
rng = np.random.RandomState(42)
keys = rng.randint(-5342534, 345345, size=3 * 2 * 1).astype(np.int32)
keys = keys.reshape((3, 2, 1))
for seed in [0, 42]:
expected = np.array([murmurhash3_32(int(k), seed)
for k in keys.flat])
expected = expected.reshape(keys.shape)
assert_array_equal(murmurhash3_32(keys, seed), expected)
for seed in [0, 42]:
expected = np.array([murmurhash3_32(k, seed, positive=True)
for k in keys.flat])
expected = expected.reshape(keys.shape)
assert_array_equal(murmurhash3_32(keys, seed, positive=True),
expected)
def test_mmhash3_bytes():
assert_equal(murmurhash3_32(b('foo'), 0), -156908512)
assert_equal(murmurhash3_32(b('foo'), 42), -1322301282)
assert_equal(murmurhash3_32(b('foo'), 0, positive=True), 4138058784)
assert_equal(murmurhash3_32(b('foo'), 42, positive=True), 2972666014)
def test_mmhash3_unicode():
assert_equal(murmurhash3_32(u('foo'), 0), -156908512)
assert_equal(murmurhash3_32(u('foo'), 42), -1322301282)
assert_equal(murmurhash3_32(u('foo'), 0, positive=True), 4138058784)
assert_equal(murmurhash3_32(u('foo'), 42, positive=True), 2972666014)
def test_no_collision_on_byte_range():
previous_hashes = set()
for i in range(100):
h = murmurhash3_32(' ' * i, 0)
assert_true(h not in previous_hashes,
"Found collision on growing empty string")
def test_uniform_distribution():
n_bins, n_samples = 10, 100000
bins = np.zeros(n_bins, dtype=np.float64)
for i in range(n_samples):
bins[murmurhash3_32(i, positive=True) % n_bins] += 1
means = bins / n_samples
expected = np.full(n_bins, 1. / n_bins)
assert_array_almost_equal(means / expected, np.ones(n_bins), 2)
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