As you show it, that's the most efficient way to do it. So, you are saying that you want to do it less efficiently, but optimized for something else. What else is it that you're optimizing for? If memory space, then you can wander over the list of keys using each without ever extracting all the keys at once, selecting one at random: 
my %hash = (populated somehow);
my ($victim_key, $victim_value);
for (0..int rand (scalar keys %hash)) { 
  ($victim_key, $victim_value) = each %hash;
}
scalar keys %hash; # reset the iterator

[download]
That'll get you the item without ever having built the entire list of keys in memory.

But if that's not what you are optimizing for, you should clarify your question. If it's simply "don't use an array", then I call homework on the question (usually signalled by a bizarre "don't use X" where "X" is the most efficient way to do something).

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

In reply to •Re: selecting random key from hash by merlyn
in thread selecting random key from hash by davidj

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