def testInverse_CountLevelSetEvent(self):
rv = self._random_variable()
event = probability.CountLevelSetEvent({'a': 1, 'x': 1})
result = rv.inverse(event)
sequences = result.all_sequences()
self.assertLen(sequences, 2)
self.assertEqual(set(sequences), {(1, 1), (1, 3)})
def testAllSequences(self):
event = probability.CountLevelSetEvent({'a': 2, 'b': 4, 'c': 1})
all_sequences = event.all_sequences()
# Number of sequences should be 7! / (4! * 2! * 1!) = 105.
self.assertLen(all_sequences, 105)
# They should all be unique.
self.assertEqual(len(all_sequences), len(set(all_sequences)))
# And check contains one correctly generated tuple.
self.assertIn(('a', 'b', 'c', 'b', 'b', 'a', 'b'), all_sequences)
def testProbability_CountLevelSetEvent(self):
base_space = probability.DiscreteProbabilitySpace({
'a': 2,
'b': 3,
'c': 5
})
space = probability.FiniteProductSpace([base_space] * 12)
event = probability.CountLevelSetEvent({'a': 7, 'b': 2, 'c': 3})
# Probability should be (12 choose 7 2 3) * p(a)^7 p(b)^2 p(c)^3
coeff = 7920
p_a = sympy.Rational(1, 5)
p_b = sympy.Rational(3, 10)
p_c = sympy.Rational(1, 2)
self.assertEqual(space.probability(event),
coeff * pow(p_a, 7) * pow(p_b, 2) * pow(p_c, 3))
def _level_set_event(values, length, verb):
"""Generates `LevelSetEvent`; see _generate_sequence_event."""
counts = combinatorics.uniform_non_negative_integers_with_sum(
len(values), length)
counts_dict = dict(list(zip(values, counts)))
event = probability.CountLevelSetEvent(counts_dict)
shuffled_values = list(values)
random.shuffle(shuffled_values)
counts_and_values = [
'{} {}'.format(counts_dict[value], value) for value in shuffled_values
if counts_dict[value] > 0
]
counts_and_values = _word_series(counts_and_values)
template = random.choice([
'{verbing} {counts_and_values}',
])
verbing = _GERUNDS[verb]
event_description = template.format(counts_and_values=counts_and_values,
verbing=verbing)
return event, event_description