[SR-Users] LCR "weight" column question

Juha Heinanen jh at tutpro.com
Fri Sep 24 09:43:23 CEST 2010


Ricardo Martinez writes:

> As you can see there is no a 20,20,20,20,10,10 call repartition.
> Could this be a bug?

ricardo,

it is a "feature" of the way randomized weights are currently
calculated.  if you have two wgs with weights 1 and 2 and then generate
two random numbers

1 * random number
2 * random number

then the probability that the latter result is less than 10 is 50 %, but
that it also is less than the first number is only 25 %.

i searched around a bit and didn't find any fast way to calculate a
better weighted random number.  the algorithms i found where based on an
idea of creating an array of gws where each gw appears in the array as
many times as its weight is and then a random number is generated
between [1, size of the array] and a gw in that random number index of
the array is selected.

any ideas on how to improve weighted random number calculation without
loosing performance?

-- juha



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