Re^2: counting instances of one array in another array

[jsmagnuson]

Thank you for this approach! This is about 10x faster than the next best approach that was suggested here that I tried implementing (which was this code from an AnonymousMonk):

my %seen;
$seen{$_}++ for @observed;
@permCounts = map { $seen{$_} || 0 } @perms;

This is good enough to get me going, but I will follow the other advice that was offered and learn about fleximal, PDL::Sparse, and hash-fu. I am very grateful for the generous advice from all of you!

best,

jim

ps -- Slight tweak: abc=(0,1,2), and then 0+(1*26^1)+(2*26^2), etc. (i.e., a=0, z=25, and when string position > 0 you multiply the index of the character in that position by 26 raised to the power of the position).

[MidLifeXis]

Re: your ps - see my ngram2number routine above. It does exactly that calculation.

Update: after re-reading my original message, I note that you also need to translate a list of characters into an alphabet to use the function (just in case it was not understood from the original code). You can do that with:

sub charlist2alphabet {
    my %results;
    for my $index ( 0 .. (@_ - 1) ) {
        $results{ $_[ $index ] } = $index;
    }
    \%results;
}

my $alphabet = charlist2alphabet( @charlist );

or

my $alphabet = { map { ( $charlist[ $_ ] => $_ ) } ( 0 .. @charlist - 
+1 );