#!/usr/local/bin/perl -w

### set density -- counts number of attacks within each n note set

my $set_size = 12;
my $previous_set = "";

foreach (<STDIN>) {
  for (my $walk = 0; $walk < (length($_) - $set_size); $walk += $set_size) {
    my $examined_set = substr($_, $walk, $set_size);
## uncomment next line to only show density where the set changes
#    next if $examined_set eq $previous_set;
    $previous_set = $examined_set;
    my $stars = $examined_set =~ tr/[1-9]/[1-9]/;
    my $star_print = "*" x $stars;
    printf("%3d | %s\n", int($walk/$set_size), $star_print);
  }
}