def test_count_past_events(self):
# Empty counts for empty results.
self.assertEqual({}, oracle.count_past_events((), LARGE_WINDOW))
# Simple case with different window sizes.
results = ('c', 'a', 'b', 'a', 'b')
self.assertEqual({'a': 1, 'b': 2},
oracle.count_past_events(results, SMALL_WINDOW))
self.assertEqual({'a': 2, 'b': 2, 'c': 1},
oracle.count_past_events(results, LARGE_WINDOW))
# Total of counts should be equal to window size.
self.assertEqual(LARGE_WINDOW, sum(self.past_counts.values()))
# All keys of past_counts should be THINGS.
self.assertNotIn(
False, [
thing in THINGS for thing in self.past_counts])
def setUp(self):
# Generate random results, calculate intermediate values for those
# results.
self.random_results = [random.choice(THINGS) for _ in range(50)]
self.past_counts = oracle.count_past_events(
self.random_results, LARGE_WINDOW)
self.weights = oracle.calculate_weights(
THINGS, self.past_counts, LARGE_WINDOW)
self.cdf = oracle.calculate_cdf(self.weights)
self.random_thing = oracle.sample_cdf(self.cdf)
def show_stats():
"""Display statistics about historical selections."""
_, results = _init_data()
count = len(results)
if count:
stats = oracle.count_past_events(results, WINDOW_SIZE)
print 'Your last %d choices included:' % count
print '\n'.join([' %sx %s' % (v, k) for (k, v) in stats.items()])
else:
print 'No activity recorded so far.'
def _check_for_uniform_distribution(testcase, results, things):
"""Check if results contain an uniform distribution of things within certain
TOLERANCE."""
dist = oracle.count_past_events(results, len(results))
num_results = len(results)
expected_count = num_results / float(len(things))
allowed_delta = TOLERANCE * num_results
for (thing, count) in dist.items():
testcase.assertAlmostEqual(
expected_count,
count,
delta=allowed_delta,
msg='In a run of %s iterations, thing "%s" appeared %d times, which is off the expected count of %d (±%d)' %
(num_results,
thing,
count,
expected_count,
TOLERANCE))
def test_calculate_weights(self):
# No existing results, all weights should be equal to base chance.
zero_counts = collections.defaultdict(int)
self.assertEqual({
'a': BASE_CHANCE,
'b': BASE_CHANCE,
'c': BASE_CHANCE,
'd': BASE_CHANCE,
}, oracle.calculate_weights(THINGS, zero_counts, LARGE_WINDOW))
# Window full of single result, weights should be split between all
# other choices.
results = ('c', 'c', 'c', 'c')
past_counts = oracle.count_past_events(results, SMALL_WINDOW)
one_third = 1 / float(3)
self.assertEqual({'a': one_third, 'b': one_third, 'd': one_third},
oracle.calculate_weights(THINGS, past_counts, SMALL_WINDOW))
# Weights should be normalized to (0, 1] range.
self.assertNotIn(False, [1 >= w >= 0 for w in self.weights.values()])
# All keys of weights should be THINGS.
self.assertNotIn(False, [thing in THINGS for thing in self.weights])