Hallo, Mathieu Bouchard hat gesagt: // Mathieu Bouchard wrote:
First, the sum all the weights should be 1. If it doesn't, or if you don't know in advance, sum all the weights.
Then build a second table, in which each element is the sum all (inclusively) previous elements of the first table. This is the sum of the previous element of the second table and the current element of the first table. This second table is the cumulative distribution.
Then generate a random number between 0 included and the sum of all weights excluded. Finally, scan the table from 0 upwards until you hit any number above the random number. That index is the output value.
Yep, that's what's used in [list-wrandom]
You don't absolutely need the second table, but it does save a bit of time afterwards.
If ever you need a much larger table, then it may become too slow, and if so, then write again and I'll explain how to accelerate it.
You made me curious: How would you recommend to make it faster for large lists?
Ciao
Frank Barknecht _ ______footils.org__