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Issue #13121: Support in-place math operators for collections.Counter().

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This commit is contained in:
Raymond Hettinger 2011-10-19 13:40:37 -07:00
parent 3bb8be6d78
commit becd56822a
4 changed files with 86 additions and 1 deletions
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21
Lib/test/test_collections.py
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@ -932,6 +932,27 @@ class TestCounter(unittest.TestCase):
set_result = setop(set(p.elements()), set(q.elements()))
self.assertEqual(counter_result, dict.fromkeys(set_result, 1))
def test_inplace_operations(self):
elements = 'abcd'
for i in range(1000):
# test random pairs of multisets
p = Counter(dict((elem, randrange(-2,4)) for elem in elements))
p.update(e=1, f=-1, g=0)
q = Counter(dict((elem, randrange(-2,4)) for elem in elements))
q.update(h=1, i=-1, j=0)
for inplace_op, regular_op in [
(Counter.__iadd__, Counter.__add__),
(Counter.__isub__, Counter.__sub__),
(Counter.__ior__, Counter.__or__),
(Counter.__iand__, Counter.__and__),
]:
c = p.copy()
c_id = id(c)
regular_result = regular_op(c, q)
inplace_result = inplace_op(c, q)
self.assertEqual(inplace_result, regular_result)
self.assertEqual(id(inplace_result), c_id)
def test_subtract(self):
c = Counter(a=-5, b=0, c=5, d=10, e=15,g=40)
c.subtract(a=1, b=2, c=-3, d=10, e=20, f=30, h=-50)