<nitpick> Before trying to benchmark it, I think I'd try tightening it up a little to eliminate some waste... 
my $fil = shift;
open (FIL, $fil) || die ("can't read $fil: $!");
my $filstr = do { local $/; <FIL> };
close FIL;

my %charhash;
$charhash{$_}++ for ( split //, $filstr );

my $ent = entropy(\%charhash, length( $filstr ));

printf ("file %s\ncontents     entropy = %30.20f\n",$fil,$ent);


sub entropy {
  my ($hashref, $total, $baselog) = @_;
  $baselog = 0.693147180559945 unless $baselog; # log(2)
  return undef unless ( ref $hashref and $total > 0 );
  my $sum;
  $sum += $_ * (log($_)/$baselog) for ( map { $_/$total } values %$has
+href );
  return -$sum;  
}

[download]
It's nice to avoid "use of map in void context", unnecessary copies of data, and "$counter++" where a simpler method (length()) will do. </nitpick>

(updated to eliminate the unnecessary "@values" array; then updated a couple more times to fix details associated with removing @values.)

In reply to Re: file/language entropy calculator by graff
in thread file/language entropy calculator by wufnik

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