I am trying to build a data structure that would be a dictionary of a dictionary of a list.
In Perl I would build the structure like so $dictionary{key1}{key2}[0] = X I would iterate like so ... foreach my $key1 ( sort keys %dictionary ) { foreach my $key2 ( sort keys %{$dictionary{$key1}} ) { foreach my $element ( @{$dictionary{$key1}{$key2} } ) { print "$key1 => $key2 => $element\n"; } } } Sorry for the Perl reference but its the language I am coming from. I use data structures like this all the time. I don't always iterate them like this but If i can learn to build these and move through them in python then a good portion of the Perl apps I am using can be ported. Playing around I have come up with this but have no clue how to iterate over it or if its the best way. It seems "clunky" but it is most likely my lack of understanding. dictionary[(key1,key2)]=[ a,b,c,d,e,f,g ... ] This i think gives me a dictionary with two keys ( not sure how to doing anything usefull with it though) and a list. Now I am not sure how I can assign one element at a time to the list. here is the pseudo code. read text file. split line from text file into list of fields. One of the fields contains the date. Split the date into two fields Year and Month/Period. Build data structure that is a dictionary based on year, based on period, based on item code then store/increment the units sold based on period. dictionary[(year,period)] = [ jan, feb, mar, apr, may, jun, july, aug, sep, oct, nov ,dec] I would prefer to have the months just be an array index 0 through 11 and when it reads the file it increments the number contained there. TIA, -- Paul Kraus =-=-=-=-=-=-=-=-=-=-= PEL Supply Company Network Administrator 216.267.5775 Voice 216.267.6176 Fax www.pelsupply.com =-=-=-=-=-=-=-=-=-=-= _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor