May 11, 2007

Uniform sampling of a data set

Sometimes you may need to sample a dataset. You may want to get a uniformly sampled subset out of a datatset stored in a file. The perlscript below does the job for you.

if ( $#ARGV!=1 ) {
        print "Wrong number of arguments\\n\\t".
                "uniform-sampler.pl <file> <sample_proportion>\\n";
}
else {
        srand();
        open(FILE,$ARGV[0]) or die "File $ARGV[0] could not be open";
        while($line=<FILE>) {
                if ( rand()<$ARGV[1] ) {
                                print $line;
                }
        }
        close FILE;
}
1;