PHP: How to generate biased random numbers

Question

I want to generate random numbers, but these numbers should be somewhat biased, so that numbers in certain ranges appear more frequently than others.

For example, to spread out a series of banner ad impressions in proportion to the number of impressions remaining for each ad campaign.

"Biased random numbers" There are so many possible jokes here. — Peter Rowell, Dec 18 '09 at 06:17
http://stackoverflow.com/questions/462219/xkcd-random-number — alex, Dec 18 '09 at 06:18
I know exactly how to generate a random biased number. `function getBiasedRandom() { return 12; }`. Its Biased, and Random! — Tyler Carter, Dec 18 '09 at 06:23
Chacha101, everybody knows that 4 is a better random number than 12 :) — Sampson, Dec 18 '09 at 06:32

score 2 · Accepted Answer · answered Dec 18 '09 at 06:16

You could generate a random number between 0 and 1, and use it as the percentage of weight for any given banner. If the number is .3 or less, then a less popular (30% of the time) banner will show. If greater, a greater (70% of the time) banner will show.

PHP: How to generate biased random numbers

1 Answers1