Question

I have this array, for example (the size is variable):

   x = ["1.111", "1.122", "1.250", "1.111"]

and I need to find the most commom value ("1.111" in this case).

Is there an easy way to do that?

Tks in advance!

EDIT #1: Thank you all for the answers!

EDIT #2: I’ve changed my accepted answer based on Z.E.D.’s information. Thank you all again!

Answer 1

Ruby < 2.2

#!/usr/bin/ruby1.8

def most_common_value(a)
  a.group_by do |e|
    e
  end.values.max_by(&:size).first
end

x = ["1.111", "1.122", "1.250", "1.111"]
p most_common_value(x)    # => "1.111"

Note: Enumberable.max_by is new with Ruby 1.9, but it has been backported to 1.8.7

Ruby >= 2.2

Ruby 2.2 introduces the Object#itself method, with which we can make the code more concise:

def most_common_value(a)
  a.group_by(&:itself).values.max_by(&:size).first
end

As a monkey patch

Or as Enumerable#mode:

Enumerable.class_eval do
  def mode
    group_by do |e|
      e
    end.values.max_by(&:size).first
  end
end

["1.111", "1.122", "1.250", "1.111"].mode
# => "1.111"