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Fix nits in itertools recipes.

This commit is contained in:
Raymond Hettinger 2010-04-02 04:49:24 +00:00
parent 601423585f
commit aeac26b9ea
1 changed files with 5 additions and 5 deletions
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10
Doc/library/itertools.rst
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@ -611,7 +611,7 @@ which incur interpreter overhead.
def ncycles(iterable, n):
"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):
return sum(map(operator.mul, vec1, vec2))
@ -707,23 +707,23 @@ which incur interpreter overhead.
def random_product(*args, repeat=1):
"Random selection from itertools.product(*args, **kwds)"
pools = [tuple(pool) for pool in args] * repeat
return [random.choice(pool) for pool in pools]
return tuple(random.choice(pool) for pool in pools)
def random_permuation(iterable, r=None):
"Random selection from itertools.permutations(iterable, r)"
pool = tuple(iterable)
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):
"Random selection from itertools.combinations(iterable, r)"
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):
"Random selection from itertools.combinations_with_replacement(iterable, r)"
pool = tuple(iterable)
return sorted(map(random.choice, repeat(pool, r)), key=pool.index)
return tuple(sorted(map(random.choice, repeat(pool, r)), key=pool.index))
Note, many of the above recipes can be optimized by replacing global lookups
with local variables defined as default values. For example, the