http://snippets.dzone.com/posts Sun, 18 May 2008 10:59:18 GMT DZone Snippets: powerset code http://snippets.dzone.com/posts/show/4895 // adds a #power_set method to Hash class <br /> <br /><code> <br /># The Array power set is stolen from http://snippets.dzone.com/posts/show/3524 <br />class Array <br /> # Returns the "power set" for this Array. This means that an array with all <br /> # subsets of the array's elements will be returned. <br /> def power_set <br /> # the power set line is stolen from http://johncarrino.net/blog/2006/08/11/powerset-in-ruby/ <br /> inject([[]]){|c,y|r=[];c.each{|i|r<<i;r<<i+[y]};r} <br /> end <br />end <br /> <br />class Hash <br /> def power_set <br /> # Returns the "power set" for this Hash. This means that a array with hashes of all <br /> # subsets of the hash's (key => value) pairs will be returned. <br /> # Example: <br /> # >> {:feedback_type=>"", :language_code=>"", :comment=>""}.power_set <br /> # <br /> # [{}, {:comment=>""}, {:language_code=>""}, {:language_code=>"", :comment=>""}, {:feedback_type=>""}, {:feedback_type=>"", :comment=>""}, {:feedback_type=>"", :language_code=>""}, {:feedback_type=>"", :language_code=>"", :comment=>""}] <br /> <br /> hash_to_array = self.to_a <br /> array_power_set = hash_to_array.power_set <br /> hash_power_set = array_power_set.collect { |pairs| pairs.inject({}) { |hash,pair| hash[pair[0]] = pair[1]; hash } } <br /> hash_power_set <br /> end <br />end <br /> <br /></code> Thu, 13 Dec 2007 12:14:16 GMT http://snippets.dzone.com/posts/show/4895 helder (Helder Ribeiro)