topic Re: trying to understand RANUNI in SAS Programming

trying to understand RANUNI

Santt0sh — Fri, 01 Jul 2022 23:28:44 GMT

Hi All,

I am trying to understand the RANUNI function. Trying to create a dataset using RANUNI

For Ex. I have a Dataset ACCOUNTS having the below-mentioned variables

ACCT_NUM, AFLAG RF1, RF2, RF3, RF4 rf2cnts

0000000001 0 0 1 1 1 1

0000000004 0 1 1 1 1 1

0000000005 0 0 0 0 1 0

000000300 0 0 0 0 0 0

I am using the below code to get a size and assign 1 rf2,rf3, and rf4 respectively if the value is 1 in a new variable (for eg. rfn)

data rf2 (drop = x n);

set accounts;

n = ranuni(5);

retain x 1;

if rfcnts eq 1 and x = 10 then do;  * x = 10 number of rf2 needed with 1;

        rf2f = 1;

        x+1;

end;

else do;

   rf2f = 0;

end;

run;

I am trying to understand when I run the same data step on the same dataset will the value of N change, have tried running the data step on the same dataset a couple of times but every 10-15 mins I still see the value of N is same. is this how it should be or change every time I run the data step with RANUNI in it and on the same dataset with the same values and size?

Kindly note I don't want to use SurveySelect, please see the output attached where we have unchanged values of N.

Kindly suggest.

Regards,

Re: trying to understand RANUNI

Tom — Sat, 02 Jul 2022 00:04:00 GMT

If you run the data step using the same SEED you should get the set series of random numbers.

If that is not what you want then use a different SEED value for each run.

Re: trying to understand RANUNI

FreelanceReinh — Sat, 02 Jul 2022 09:17:21 GMT

Hi @Santt0sh,

If you want n to change in virtually every run of the program, you can use the seed 0, i.e., n = ranuni(0). Then "the time of day is used to initialize the seed stream" (documentation), hence the automatic change. From the resulting random numbers (if you do not drop n from dataset RF2) you can even determine a non-zero seed that can be used to reproduce the same results, if needed.

Re: trying to understand RANUNI

Santt0sh — Tue, 05 Jul 2022 16:04:26 GMT

Thank You for your quick response and this was helpful.