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authorRaymond Hettinger <python@rcn.com>2003-09-06 04:25:54 (GMT)
committerRaymond Hettinger <python@rcn.com>2003-09-06 04:25:54 (GMT)
commit66d09f1b3029d9cf975ccf26c437c9fb2605db91 (patch)
treeb8c031f72f6109de1be68664fc391c9a334a3f28 /Lib/random.py
parentc8b08b446a95694cf246c3fd92c1bc656944d68f (diff)
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SF bug #801342: Bug (documentation or real, your choice) in random.sample.
random.sample() uses one of two algorithms depending on the ratio of the sample size to the population size. One of the algorithms accepted any iterable population argument so long as it defined __len__(). The other had a stronger requirement that the population argument be indexable. While it met the documentation specifications which insisted that the population argument be a sequence, it made random.sample() less usable with sets. So, the second algorithm was modified to coerce non-indexable iterables and dictionaries into a tuple before proceeding.
Diffstat (limited to 'Lib/random.py')
-rw-r--r--Lib/random.py4
1 files changed, 4 insertions, 0 deletions
diff --git a/Lib/random.py b/Lib/random.py
index 7210f62..2530c39 100644
--- a/Lib/random.py
+++ b/Lib/random.py
@@ -258,6 +258,10 @@ class Random(_random.Random):
result[i] = pool[j]
pool[j] = pool[n-i-1] # move non-selected item into vacancy
else:
+ try:
+ n > 0 and (population[0], population[n//2], population[n-1])
+ except (TypeError, KeyError): # handle sets and dictionaries
+ population = tuple(population)
selected = {}
for i in xrange(k):
j = _int(random() * n)