Perl is certainly often not the best tool. But if it comes to sed and awk it's hard to believe

Yes, this was my point.

I bet, I could easily translate this given awk script in a one2one fashion to Perl, by encapsulating the open on demand into a short sub.

You don't need to, Larry did that already :-) a2p was part of the Perl core until 5.20, now it lives on CPAN.

$ a2p 11121118.awk 
#!/usr/bin/perl
eval 'exec /usr/bin/perl -S $0 ${1+"$@"}'
    if $running_under_some_shell;
                        # this emulates #! processing on NIH machines.
                        # (remove #! line above if indigestible)

eval '$'.$1.'$2;' while $ARGV[0] =~ /^([A-Za-z_0-9]+=)(.*)/ && shift;
                        # process any FOO=bar switches

$FS = ' ';              # set field separator
$, = ' ';               # set output field separator
$\ = "\n";              # set output record separator

$FS = "\t";

line: while (<>) {
    chomp;        # strip record separator
    @Fld = split($FS, $_, -1);
    if (($.-$FNRbase) == 1) {
        @Fields = split($FS, '', -1);   # clear fields array
        for ($i = 1; $i <= ($#Fld+1); $i++) {
            $Fields[($i)-1] = $Fld[$i];
        }
        next line;
    }
    for ($i = 1; $i <= ($#Fld+1); $i++) {
        &Pick('>', $Fields[($i)-1]) &&
            (print $fh $Fld[$i]);
    }
}
continue {
    $FNRbase = $. if eof;
}

sub Pick {
    local($mode,$name,$pipe) = @_;
    $fh = $name;
    open($name,$mode.$name.$pipe) unless $opened{$name}++;
}

[download]

Unfortunately, there's apparently a bug in the translator, and the above script needs a s/\$Fld\[\$i\K\]/-1]/g to fix it.

In reply to Re^8: Split tab-separated file into separate files, based on column name (open on demand) by haukex
in thread Split tab-separated file into separate files, based on column name by Anonymous Monk

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