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Commit9cb30bb

Browse files
Move random selection recipes from itertools.rst to random.rst (GH-98369)
(cherry picked from commit70732d8)Co-authored-by: Raymond Hettinger <rhettinger@users.noreply.github.com>
1 parent6c7f7ec commit9cb30bb

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2 files changed

+31
-25
lines changed

2 files changed

+31
-25
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‎Doc/library/itertools.rst

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@@ -1000,31 +1000,6 @@ which incur interpreter overhead.
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# first_true([a,b], x, f) --> a if f(a) else b if f(b) else x
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return next(filter(pred, iterable), default)
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def random_product(*args, repeat=1):
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"Random selection from itertools.product(*args, **kwds)"
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pools = [tuple(pool) for pool in args] * repeat
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return tuple(map(random.choice, pools))
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def random_permutation(iterable, r=None):
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"Random selection from itertools.permutations(iterable, r)"
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pool = tuple(iterable)
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r = len(pool) if r is None else r
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return tuple(random.sample(pool, r))
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def random_combination(iterable, r):
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"Random selection from itertools.combinations(iterable, r)"
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pool = tuple(iterable)
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n = len(pool)
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indices = sorted(random.sample(range(n), r))
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return tuple(pool[i] for i in indices)
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def random_combination_with_replacement(iterable, r):
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"Random selection from itertools.combinations_with_replacement(iterable, r)"
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pool = tuple(iterable)
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n = len(pool)
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indices = sorted(random.choices(range(n), k=r))
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return tuple(pool[i] for i in indices)
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def nth_combination(iterable, r, index):
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"Equivalent to list(combinations(iterable, r))[index]"
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pool = tuple(iterable)

‎Doc/library/random.rst

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@@ -564,6 +564,37 @@ Simulation of arrival times and service deliveries for a multiserver queue::
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Recipes
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-------
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These recipes show how to efficiently make random selections
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from the combinatoric iterators in the:mod:`itertools` module:
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..testcode::
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import random
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def random_product(*args, repeat=1):
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"Random selection from itertools.product(*args, **kwds)"
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pools = [tuple(pool) for pool in args] * repeat
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return tuple(map(random.choice, pools))
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def random_permutation(iterable, r=None):
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"Random selection from itertools.permutations(iterable, r)"
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pool = tuple(iterable)
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r = len(pool) if r is None else r
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return tuple(random.sample(pool, r))
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def random_combination(iterable, r):
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"Random selection from itertools.combinations(iterable, r)"
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pool = tuple(iterable)
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n = len(pool)
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indices = sorted(random.sample(range(n), r))
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return tuple(pool[i] for i in indices)
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def random_combination_with_replacement(iterable, r):
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"Random selection from itertools.combinations_with_replacement(iterable, r)"
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pool = tuple(iterable)
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n = len(pool)
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indices = sorted(random.choices(range(n), k=r))
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return tuple(pool[i] for i in indices)
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The default:func:`.random` returns multiples of 2⁻⁵³ in the range
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*0.0 ≤ x < 1.0*. All such numbers are evenly spaced and are exactly
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representable as Python floats. However, many other representable

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