1,ABC,X,1.203000e+02
1,ABC,Y,7.830000e+00
2,DEF,X,1.212400e+02
2,DEF,Y,8.810000e+00
3,GHI,X,1.180700e+02
3,GHI,Y,8.550000e+00
5,JKL,X,1.193500e+02
5,JKL,Y,7.270000e+00
.
.
.

##</code><code>##

while (<NEWDATA>){ # where NEWDATA points to a file with the comma delimited data
    $currLine = $_; # current, comma-delimited line
    chomp $currLine;
    @formatDataArray = split(/,/,$currLine); #split at comma
    push (@newArray, $formatDataArray[0]); # push first column into newArray
#    print OUT "@newArray\n";
}

foreach my $item(@newArray){ # get unique array elements
    $seen{$item}++;
}

# numerical sort on keys and add to array
@uniq = sort {$seen{$a} <=>  $seen{$b} } keys %seen;

# print to see if things look right
foreach my $element(@uniq){
    print OUT "$element\n";
}


##</code><code>##

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