jkaihsu
3/7/2013 - 8:16 AM

Write a method mode which takes an Array of numbers as its input and returns an Array of the most frequent values. If there's only one mo

Write a method mode which takes an Array of numbers as its input and returns an Array of the most frequent values.

If there's only one most-frequent value, it returns a single-element Array.

For example,

mode([1,2,3,3]) # => [3] mode([4.5, 0, 0]) # => [0] mode([1.5, -1, 1, 1.5]) # => [1.5] mode([1,1,2,2]) # => [1,2] mode([1,2,3]) # => [1,2,3], because all occur with equal frequency

mode.rb
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def mode(array)
  mode = array.inject(Hash.new(0)) { |h,v| h[v] = h[v] + 1; h}
  mode.select{ |h,v| v == mode.values.max }.keys
end