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Code Issues Releases Wiki Activity

Cleanup itertools recipes

This commit is contained in:
Raymond Hettinger 2010-04-02 06:21:59 +00:00
parent ce2338a16b
commit b640bcc32b
1 changed files with 8 additions and 8 deletions
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16
Doc/library/itertools.rst
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@ -663,7 +663,7 @@ which incur interpreter overhead.
def ncycles(iterable, n): def ncycles(iterable, n):
"Returns the sequence elements n times" "Returns the sequence elements n times"
return chain.from_iterable(repeat(iterable, n)) return chain.from_iterable(repeat(tuple(iterable), n))
def dotproduct(vec1, vec2): def dotproduct(vec1, vec2):
return sum(imap(operator.mul, vec1, vec2)) return sum(imap(operator.mul, vec1, vec2))
@ -782,23 +782,23 @@ which incur interpreter overhead.
def random_product(*args, **kwds): def random_product(*args, **kwds):
"Random selection from itertools.product(*args, **kwds)" "Random selection from itertools.product(*args, **kwds)"
pools = map(tuple, args) * kwds.get('repeat', 1) pools = map(tuple, args) * kwds.get('repeat', 1)
return map(random.choice, pools) return tuple(random.choice(pool) for pool in pools)
def random_permuation(iterable, r=None): def random_permuation(iterable, r=None):
"Random selection from itertools.permutations(iterable, r)" "Random selection from itertools.permutations(iterable, r)"
pool = list(iterable) pool = tuple(iterable)
r = len(pool) if r is None else r r = len(pool) if r is None else r
return random.sample(pool, r) return tuple(random.sample(pool, r))
def random_combination(iterable, r): def random_combination(iterable, r):
"Random selection from itertools.combinations(iterable, r)" "Random selection from itertools.combinations(iterable, r)"
pool = list(iterable) pool = tuple(iterable)
return sorted(random.sample(pool, r), key=pool.index) return tuple(sorted(random.sample(pool, r), key=pool.index))
def random_combination_with_replacement(iterable, r): def random_combination_with_replacement(iterable, r):
"Random selection from itertools.combinations_with_replacement(iterable, r)" "Random selection from itertools.combinations_with_replacement(iterable, r)"
pool = list(iterable) pool = tuple(iterable)
return sorted(imap(random.choice, [pool]*r), key=pool.index) return tuple(sorted(imap(random.choice, [pool]*r), key=pool.index))
Note, many of the above recipes can be optimized by replacing global lookups Note, many of the above recipes can be optimized by replacing global lookups
with local variables defined as default values. For example, the with local variables defined as default values. For example, the