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Old 06-29-2009
Dedalus Dedalus is offline
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Join Date: May 2009
Location: Italy/France
Posts: 60
Uniform sampling

Hi

My goal is to build a C function that perform a uniform sampling. I mean that I have a big file with a lot of data and I'd like to take just some data samples accordly the uniform distribution.

Es.
file1: a b c d e f g h i l m n o p q

An example would be to flip a coin for each letter and select all letters
for which the coin showed the head.

I have used the srand() system call, but it is not uniform.
Can anyone suggest a way to start?
Thanks

D


---------- Post updated at 08:00 PM ---------- Previous update was at 06:30 PM ----------

Hi i'm trying in this way:


Code:
......
#define RAND_MAX 2
 srand(time(NULL));
 ....... in the loop

p=rand()%RAND_MAX

and if the index is greater than 0 grab the letter otherwise leave it.
If you have a different suggestion let me know

thanks
D.