You can just open each file once: (untested) 
my @outfiles;
open $outfiles[$_], "> $ARGV[0].$_" or die "nope: $!" for 0..$n-1;
...
        print {$outfiles[$i]} join("\t",$id,@elmt[@ind[$d..$f]])."\n";

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In reply to Re: A vertical (+/- random) split of a file by ysth
in thread A vertical (+/- random) split of a file by Marsel

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