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Simplify explanation of multiset operations by removing restrictions on negative inputs.

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This commit is contained in:
Raymond Hettinger 2009-01-21 20:36:27 +00:00
parent 63b3a97a2a
commit e0d1b9f11f
3 changed files with 17 additions and 24 deletions
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17
Lib/test/test_collections.py
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@ -462,18 +462,19 @@ class TestCounter(unittest.TestCase):
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))
for counterop, numberop, defneg in [
(Counter.__add__, lambda x, y: x+y if x+y>0 else 0, True),
(Counter.__sub__, lambda x, y: x-y if x-y>0 else 0, False),
(Counter.__or__, max, False),
(Counter.__and__, min, False),
q.update(h=1, i=-1, j=0)
for counterop, numberop in [
(Counter.__add__, lambda x, y: max(0, x+y)),
(Counter.__sub__, lambda x, y: max(0, x-y)),
(Counter.__or__, lambda x, y: max(0,x,y)),
(Counter.__and__, lambda x, y: max(0, min(x,y))),
]:
result = counterop(p, q)
for x in elements:
# all except __add__ are undefined for negative inputs
if defneg or (p[x] >= 0 and q[x] >= 0):
self.assertEqual(numberop(p[x], q[x]), result[x])
self.assertEqual(numberop(p[x], q[x]), result[x],
(counterop, x, p, q))
# verify that results exclude non-positive counts
self.assert_(x>0 for x in result.values())