Programming Perl, 4th Edition

Hashes of Arrays

Use a hash of arrays when you want to look up each array by a particular string rather than merely by an index number. In our example of television characters, instead of looking up the list of names by the zeroth show, the first show, and so on, we’ll set it up so we can look up the cast list given the name of the show.

Because our outer data structure is a hash, we can’t order the contents, but we can use the sort function to specify a particular output order.