#!/usr/bin/perl

use strict;
use warnings;

my $ifile = '/home/osotolongo/facehbi/dicom_mri_v2_pre_date.csv';
my $ofile = '/home/osotolongo/facehbi/dicom_mri_v2_date.csv';
my %imgdates;

open IDF, "<$ifile" or die "No such file!";
while (<IDF>){
        (my $subject, my $imdate) = /(.*);(.*)/;
        if (exists($imgdates{$subject})){
                $imgdates{$subject} = $imdate unless ($imgdates{$subject} > $imdate);
        }else{
                $imgdates{$subject} = $imdate;
        }
}
close IDF;
open ODF, ">$ofile" or die "Couldn't create file";
foreach my $subject (sort keys %imgdates){
        print ODF "$subject;$imgdates{$subject}\n";
}
close ODF;