my $margin = 500;
open my $SC, "<", $file2 or die "Error: could not open $file2 $!";
my %result;
my $step = 100;
while (my $line2 = <$SC>) 
{
    my ($id, $val) = split /\t/, $line2;
    my $val_file1 = $hash{$id};
    my ($low, $high) = ( $val_file1 - $margin, $val_file1 + $margin);
    next unless $val > $low and $val < $high; # value not within range, just discard it
    my $delta = int (($val - $low)/$step); # delta : slot number
    $result{$id}{$delta}++;
}
close $SC;

# now %result has, for each $ID, a frequency distribution by steps of 100 (slots 0 to 9), we just need to extract the data from it.
for my $id (keys %result) {
    my $low = $hash{$id} - $margin;
    for my $slot (0..9){
        my $range = sprintf "%d-%d", $low + $slot * $step, $low + ($slot + 1) * $step;
        my $frequency = $result{$id}{$slot} // 0;
        print "ID $id: $range : $frequency \n";
    }
}