It is possible to do it without constructing the threshold array by stepping through the hash a second time. 
my $total = 0;
foreach my $key (keys %hash) {
    $total += $hash->{$key};
}

my $r = int(rand($total));

my $sum = 0;
foreach my $key (keys %$hash) {
    $sum += $hash->{$key};
    if ($r < $sum) 
        return $key;
}

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It might be possible to do only one pass through the hash using a technique like finding a random line from a file when the number of lines in the file isn't known.

In reply to Re: Re: Random Hash Key according to key frequency by iburrell
in thread Random Hash Key according to key frequency by artist

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