#!/usr/bin/perl 

use strict;
use warnings;
use Data::Dumper;

my @AoH;

my @fields = qw(subject grade rank);

while (my $record = <DATA>){
  chomp $record;
  my @values = $record =~ /([^,]+)/g;
  push @AoH, {
    map {$fields[$_] => $values[$_]} (0..$#fields)
  };
}

print Dumper \@AoH;

__DATA__
english,1,1
history,2,2
science,3,3
biology,4,4