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Add recipe for subslices (GH-31028)

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Raymond Hettinger 2022-02-01 22:18:52 -06:00 committed by GitHub
parent f77beacf01
commit 06a491179f
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9
Doc/library/itertools.rst
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@ -893,6 +893,12 @@ which incur interpreter overhead.
yield from it
return true_iterator(), remainder_iterator()
def subslices(seq):
"Return all contiguous non-empty subslices of a sequence"
# subslices('ABCD') --> A AB ABC ABCD B BC BCD C CD D
slices = starmap(slice, combinations(range(len(seq) + 1), 2))
return map(operator.getitem, repeat(seq), slices)
def powerset(iterable):
"powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
s = list(iterable)
@ -1188,6 +1194,9 @@ which incur interpreter overhead.
>>> ''.join(remainder)
'dEfGhI'
>>> list(subslices('ABCD'))
['A', 'AB', 'ABC', 'ABCD', 'B', 'BC', 'BCD', 'C', 'CD', 'D']
>>> list(powerset([1,2,3]))
[(), (1,), (2,), (3,), (1, 2), (1, 3), (2, 3), (1, 2, 3)]