diff options
| -rw-r--r-- | Doc/library/itertools.rst | 8 | ||||
| -rw-r--r-- | Lib/test/test_itertools.py | 12 |
2 files changed, 8 insertions, 12 deletions
diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst index db10b6d..36254cd 100644 --- a/Doc/library/itertools.rst +++ b/Doc/library/itertools.rst @@ -590,11 +590,9 @@ which incur interpreter overhead. nexts = cycle(islice(nexts, pending)) def powerset(iterable): - "powerset('ab') --> set([]), set(['a']), set(['b']), set(['a', 'b'])" - # Recipe credited to Eric Raymond - pairs = [(2**i, x) for i, x in enumerate(iterable)] - for n in xrange(2**len(pairs)): - yield set(x for m, x in pairs if m&n) + "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)" + s = list(iterable) + return chain.from_iterable(combinations(s, r) for r in range(len(s)+1)) def compress(data, selectors): "compress('ABCDEF', [1,0,1,0,1,1]) --> A C E F" diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py index ba55d23..7023b29 100644 --- a/Lib/test/test_itertools.py +++ b/Lib/test/test_itertools.py @@ -1277,11 +1277,9 @@ Samuele ... nexts = cycle(islice(nexts, pending)) >>> def powerset(iterable): -... "powerset('ab') --> set([]), set(['a']), set(['b']), set(['a', 'b'])" -... # Recipe credited to Eric Raymond -... pairs = [(2**i, x) for i, x in enumerate(iterable)] -... for n in range(2**len(pairs)): -... yield set(x for m, x in pairs if m&n) +... "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)" +... s = list(iterable) +... return chain.from_iterable(combinations(s, r) for r in range(len(s)+1)) >>> def compress(data, selectors): ... "compress('ABCDEF', [1,0,1,0,1,1]) --> A C E F" @@ -1379,8 +1377,8 @@ perform as purported. >>> list(roundrobin('abc', 'd', 'ef')) ['a', 'd', 'e', 'b', 'f', 'c'] ->>> list(map(sorted, powerset('ab'))) -[[], ['a'], ['b'], ['a', 'b']] +>>> list(powerset([1,2,3])) +[(), (1,), (2,), (3,), (1, 2), (1, 3), (2, 3), (1, 2, 3)] >>> list(compress('abcdef', [1,0,1,0,1,1])) ['a', 'c', 'e', 'f'] |