From: Ryan Leavengood <mrcode@...>
Date: 2005-06-26T23:54:15+09:00
Subject: Re: grouping/sorting [newbie question]

bdarcus@gmail.com wrote:
> 
> However, while I figured out how to sort the list correctly, I don't
> really understand how to do the grouping. Could someone please explain?

Inject is your friend:

require 'yaml'

films = YAML::load(File.open("film.yaml"))

grouped_comments = films.inject({}) do |grouped, film|
   (grouped[film['title']] ||= []) << film['comments']
   grouped
end

grouped_comments.keys.sort.each do |title|
   puts "Comments for #{title}:"
   grouped_comments[title].each do |comment|
     puts "\t#{comment}"
   end
end

Ryan