Hash invert in Ruby?

Question

I\'ve got a hash of the format:

{key1 => [a, b, c], key2 => [d, e, f]}

and I want to end up with:

{ a => key1, b =         


        

Answer 1

new_hash={}
hash = {"key1" => ['a', 'b', 'c'], "key2" => ['d','e','f']}
hash.each_pair{|key, val|val.each{|v| new_hash[v] = key }}

This gives

new_hash # {"a"=>"key1", "b"=>"key1", "c"=>"key1", "d"=>"key2", "e"=>"key2", "f"=>"key2"}