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@ -344,10 +344,12 @@ class Random(_random.Random):
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the selections are made with equal probability.
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"""
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random = self.random
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if cum_weights is None:
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if weights is None:
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choice = self.choice
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return [choice(population) for i in range(k)]
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_int = int
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total = len(population)
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return [population[_int(random() * total)] for i in range(k)]
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else:
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cum_weights = list(_itertools.accumulate(weights))
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elif weights is not None:
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@ -355,7 +357,6 @@ class Random(_random.Random):
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if len(cum_weights) != len(population):
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raise ValueError('The number of weights does not match the population')
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bisect = _bisect.bisect
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random = self.random
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total = cum_weights[-1]
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return [population[bisect(cum_weights, random() * total)] for i in range(k)]
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@ -625,6 +625,22 @@ class MersenneTwister_TestBasicOps(TestBasicOps, unittest.TestCase):
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self.assertTrue(stop < x <= start)
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self.assertEqual((x+stop)%step, 0)
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def test_choices_algorithms(self):
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# The various ways of specifing weights should produce the same results
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choices = self.gen.choices
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n = 13132817
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self.gen.seed(8675309)
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a = self.gen.choices(range(n), k=10000)
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self.gen.seed(8675309)
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b = self.gen.choices(range(n), [1]*n, k=10000)
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self.assertEqual(a, b)
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self.gen.seed(8675309)
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c = self.gen.choices(range(n), cum_weights=range(1, n+1), k=10000)
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self.assertEqual(a, c)
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def gamma(z, sqrt2pi=(2.0*pi)**0.5):
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# Reflection to right half of complex plane
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if z < 0.5:
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