[ python-Bugs-1460340 ] random.sample can raise KeyError

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Bugs item #1460340, was opened at 2006-03-28 19:05
Message generated for change (Comment added) made by rhettinger
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Category: Python Library
Group: Python 2.3
Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: paul rubin (phr)
Assigned to: Nobody/Anonymous (nobody)
Summary: random.sample can raise KeyError

Initial Comment:
I have only tested this in 2.3 and the relevant code in
random.py has changed in the current svn branch, but
from inspection it looks to me like the bug may still
be there.

If you initialize a dictionary as follows:

 a={}.fromkeys(range(10)+range(10,100,2)+range(100,110))

then

 random.sample(a,3)

raises KeyError most times that you call it.


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>Comment By: Raymond Hettinger (rhettinger)
Date: 2006-03-29 04:17

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Checked-in a fix.
See revision 43420 and 43421.

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Comment By: Georg Brandl (gbrandl)
Date: 2006-03-29 04:11

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random.sample is documented to take a sequence as its first
argument. A dict is not a sequence type.

I think you want
random.sample(a.keys(), 3)
or, for large dicts,
random.sample(a.iterkeys(), 3)

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