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Add tests to verify combinatoric relationships.

This commit is contained in:
Raymond Hettinger 2009-01-27 09:33:06 +00:00
parent 1763f8adb4
commit 2976aaa396
1 changed files with 26 additions and 0 deletions
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26
Lib/test/test_itertools.py
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@ -106,6 +106,14 @@ class TestBasicOps(unittest.TestCase):
if sorted(indices) == list(indices):
yield tuple(pool[i] for i in indices)
def combinations3(iterable, r):
'Pure python version from cwr()'
pool = tuple(iterable)
n = len(pool)
for indices in combinations_with_replacement(range(n), r):
if len(set(indices)) == r:
yield tuple(pool[i] for i in indices)
for n in range(7):
values = [5*x-12 for x in range(n)]
for r in range(n+2):
@ -122,6 +130,7 @@ class TestBasicOps(unittest.TestCase):
[e for e in values if e in c]) # comb is a subsequence of the input iterable
self.assertEqual(result, list(combinations1(values, r))) # matches first pure python version
self.assertEqual(result, list(combinations2(values, r))) # matches second pure python version
self.assertEqual(result, list(combinations3(values, r))) # matches second pure python version
# Test implementation detail: tuple re-use
self.assertEqual(len(set(map(id, combinations('abcde', 3)))), 1)
@ -261,6 +270,23 @@ class TestBasicOps(unittest.TestCase):
self.assertEqual(len(set(map(id, permutations('abcde', 3)))), 1)
self.assertNotEqual(len(set(map(id, list(permutations('abcde', 3))))), 1)
def test_combinatorics(self):
# Test relationships between product(), permutations(),
# combinations() and combinations_with_replacement().
s = 'ABCDE'
for r in range(8):
prod = list(product(s, repeat=r))
cwr = list(combinations_with_replacement(s, r))
perm = list(permutations(s, r))
comb = list(combinations(s, r))
self.assertEquals(cwr, [t for t in prod if sorted(t)==list(t)]) # cwr: prods which are sorted
self.assertEquals(perm, [t for t in prod if len(set(t))==r]) # perm: prods with no dups
self.assertEqual(comb, [t for t in perm if sorted(t)==list(t)]) # comb: perms that are sorted
self.assertEqual(comb, [t for t in cwr if len(set(t))==r]) # comb: cwrs without dups
self.assertEqual(set(comb), set(cwr) & set(perm)) # comb: both a cwr and a perm
def test_compress(self):
self.assertEqual(list(compress('ABCDEF', [1,0,1,0,1,1])), list('ACEF'))
self.assertEqual(list(compress('ABCDEF', [0,0,0,0,0,0])), list(''))