You can swap memory for time to do this in O(1). Populate an array with your values in the distribution you want, and select a random index.
Your example, ( 1, 1.25, 3.6, 2), is ( 20/20, 25/20, 72/20, 40/20), so:
{
my @dist = (
(0) x 20,
(1) x 25,
(2) x 72,
(3) x 40
);
sub choose_weighted {
$dist[ rand(@dist)];
}
}
If time is not an issue, your method is fine, except that < is probably better than <= in the comparisons. That is because rand() returns a number less than one.
After Compline, Zaxo
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