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bpo-40755: Add missing multiset operations to Counter() (GH-20339)

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Raymond Hettinger 2020-05-28 08:35:46 -07:00 • committed by GitHub
parent 0de437de62
commit 60398512c8
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4 changed files with 206 additions and 6 deletions
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59
Lib/test/test_collections.py
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@ -7,6 +7,7 @@ import inspect
import operator
import pickle
from random import choice, randrange
from itertools import product, chain, combinations
import string
import sys
from test import support
@ -2219,6 +2220,64 @@ class TestCounter(unittest.TestCase):
self.assertTrue(c.called)
self.assertEqual(dict(c), {'a': 5, 'b': 2, 'c': 1, 'd': 1, 'r':2 })
def test_multiset_operations_equivalent_to_set_operations(self):
# When the multiplicities are all zero or one, multiset operations
# are guaranteed to be equivalent to the corresponding operations
# for regular sets.
s = list(product(('a', 'b', 'c'), range(2)))
powerset = chain.from_iterable(combinations(s, r) for r in range(len(s)+1))
counters = [Counter(dict(groups)) for groups in powerset]
for cp, cq in product(counters, repeat=2):
sp = set(cp.elements())
sq = set(cq.elements())
self.assertEqual(set(cp + cq), sp | sq)
self.assertEqual(set(cp - cq), sp - sq)
self.assertEqual(set(cp | cq), sp | sq)
self.assertEqual(set(cp & cq), sp & sq)
self.assertEqual(cp.isequal(cq), sp == sq)
self.assertEqual(cp.issubset(cq), sp.issubset(sq))
self.assertEqual(cp.issuperset(cq), sp.issuperset(sq))
self.assertEqual(cp.isdisjoint(cq), sp.isdisjoint(sq))
def test_multiset_equal(self):
self.assertTrue(Counter(a=3, b=2, c=0).isequal('ababa'))
self.assertFalse(Counter(a=3, b=2).isequal('babab'))
def test_multiset_subset(self):
self.assertTrue(Counter(a=3, b=2, c=0).issubset('ababa'))
self.assertFalse(Counter(a=3, b=2).issubset('babab'))
def test_multiset_superset(self):
self.assertTrue(Counter(a=3, b=2, c=0).issuperset('aab'))
self.assertFalse(Counter(a=3, b=2, c=0).issuperset('aabd'))
def test_multiset_disjoint(self):
self.assertTrue(Counter(a=3, b=2, c=0).isdisjoint('cde'))
self.assertFalse(Counter(a=3, b=2, c=0).isdisjoint('bcd'))
def test_multiset_predicates_with_negative_counts(self):
# Multiset predicates run on the output of the elements() method,
# meaning that zero counts and negative counts are ignored.
# The tests below confirm that we get that same results as the
# tests above, even after a negative count has been included
# in either *self* or *other*.
self.assertTrue(Counter(a=3, b=2, c=0, d=-1).isequal('ababa'))
self.assertFalse(Counter(a=3, b=2, d=-1).isequal('babab'))
self.assertTrue(Counter(a=3, b=2, c=0, d=-1).issubset('ababa'))
self.assertFalse(Counter(a=3, b=2, d=-1).issubset('babab'))
self.assertTrue(Counter(a=3, b=2, c=0, d=-1).issuperset('aab'))
self.assertFalse(Counter(a=3, b=2, c=0, d=-1).issuperset('aabd'))
self.assertTrue(Counter(a=3, b=2, c=0, d=-1).isdisjoint('cde'))
self.assertFalse(Counter(a=3, b=2, c=0, d=-1).isdisjoint('bcd'))
self.assertTrue(Counter(a=3, b=2, c=0, d=-1).isequal(Counter(a=3, b=2, c=-1)))
self.assertFalse(Counter(a=3, b=2, d=-1).isequal(Counter(a=2, b=3, c=-1)))
self.assertTrue(Counter(a=3, b=2, c=0, d=-1).issubset(Counter(a=3, b=2, c=-1)))
self.assertFalse(Counter(a=3, b=2, d=-1).issubset(Counter(a=2, b=3, c=-1)))
self.assertTrue(Counter(a=3, b=2, c=0, d=-1).issuperset(Counter(a=2, b=1, c=-1)))
self.assertFalse(Counter(a=3, b=2, c=0, d=-1).issuperset(Counter(a=2, b=1, c=-1, d=1)))
self.assertTrue(Counter(a=3, b=2, c=0, d=-1).isdisjoint(Counter(c=1, d=2, e=3, f=-1)))
self.assertFalse(Counter(a=3, b=2, c=0, d=-1).isdisjoint(Counter(b=1, c=1, d=1, e=-1)))
################################################################################
### Run tests