[Python-checkins] r79919 - python/branches/release26-maint/Doc/library/itertools.rst
raymond.hettinger
python-checkins at python.org
Sat Apr 10 08:51:41 CEST 2010
Author: raymond.hettinger
Date: Sat Apr 10 08:51:41 2010
New Revision: 79919
Log:
Fixup new itertools recipes.
Modified:
python/branches/release26-maint/Doc/library/itertools.rst
Modified: python/branches/release26-maint/Doc/library/itertools.rst
==============================================================================
--- python/branches/release26-maint/Doc/library/itertools.rst (original)
+++ python/branches/release26-maint/Doc/library/itertools.rst Sat Apr 10 08:51:41 2010
@@ -784,7 +784,7 @@
pools = map(tuple, args) * kwds.get('repeat', 1)
return tuple(random.choice(pool) for pool in pools)
- def random_permuation(iterable, r=None):
+ def random_permutation(iterable, r=None):
"Random selection from itertools.permutations(iterable, r)"
pool = tuple(iterable)
r = len(pool) if r is None else r
@@ -793,12 +793,16 @@
def random_combination(iterable, r):
"Random selection from itertools.combinations(iterable, r)"
pool = tuple(iterable)
- return tuple(sorted(random.sample(pool, r), key=pool.index))
+ n = len(pool)
+ indices = sorted(random.sample(xrange(n), r))
+ return tuple(pool[i] for i in indices)
def random_combination_with_replacement(iterable, r):
"Random selection from itertools.combinations_with_replacement(iterable, r)"
pool = tuple(iterable)
- return tuple(sorted(imap(random.choice, [pool]*r), key=pool.index))
+ n = len(pool)
+ indices = sorted(random.randrange(n) for i in xrange(r))
+ return tuple(pool[i] for i in indices)
Note, many of the above recipes can be optimized by replacing global lookups
with local variables defined as default values. For example, the
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