Re: Pulling Random Records from a file -- RPG400-L

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JMBauman@xxxxxxxxxxxxxxxx wrote:

Wanted to get some feedback about possible options to pull random records
from a file.   I am dealing with an invoice file for a date (one day) for
multiple locations.  I need to pull thirty random bills from this file for
a date and the number of bills I pull for a location must be proportionate
to that location's number of bills compared to number of bill's for all
locations.  With that being said, my quandary is how to pull these bills
randomly.  My first attempt at this, I read through the file and selected a
record every "random" number of seconds.  This was not random enough as I
was always grabbing my bills from the first hundred records for every
location (about 500 records per location).  Any thoughts would be greatly
appreciated.

First, get the number of records in the file. After the file is opened, the number is in position 156-159 in the INFDS.

Next, use your favorite method to compute random numbers (such as the C runtime library function "rand()"), and convert them to the range computed in the first step. Compute as many as you need, checking for duplicates.

Finally, read the records by relative record number.

Cheers! Hans

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