From: gwtmp01@...
Date: 2005-12-01T07:24:16+09:00
Subject: Re: Help constructing interesting hash?


On Nov 30, 2005, at 4:57 PM, Chris McMahon wrote:
> Now suppose I have a AoA like
>
> [[A, B, C,][1,2,2]]
>
> Is there a readable way to construct a hash like
>
> 1=>[A]
> 2=>[B, C]

input = [[:A, :B, :C],[1,2,2]]

output = {}
input[1].each_with_index { |group, index|  (output[group] ||= []) <<  
input[0][index] }

puts "input: #{input.inspect}"
puts "output: #{output.inspect}"
----------------
input: [[:A, :B, :C], [1, 2, 2]]
output: {1=>[:A], 2=>[:B, :C]}