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Categories / Ruby / Collections

 

Sorting an Array by Frequency of Appearance

module Enumerable   def sort_by_frequency     histogram = inject(Hash.new(0)) { |hash, x| hash[x] += 1; hash}     sort_by { |x| [histogram[x], x] }   end end p [1,2,3,4,1,2,4,8,1,4,9,16].sort_by_frequency