Ruby script to rank array items, considering same ranks.

array_rank.rb

#! /usr/local/bin/ruby
# coding: utf-8
#**********************************************************
# Ruby script to rank array items, considering same ranks.
#**********************************************************
#
class Array
  def rank
    # 以下の場合は例外スロー
    # - 自身配列が空
    # - 自身配列に数値以外の値を含む
    raise "Self array is nil!" if self.size == 0
    self.each do |v|
      raise "Items except numerical values exist!" unless v.to_s =~ /[\d\.]+/
    end

    # ランク付け
    self.map { |v| self.count { |a| a > v } + 1 }
  end
end

a = [9, 3, 2, 7, 1, 6, 8, 5, 10, 4]
b = [6, 8, 5, 8, 4, 9, 3, 3, 7, 1]
c = [6, 8.5, 5, 3.2, 7, 1, 8.1, 3.2, 9, 3]
d = [9, 3, 2, 7, "abc", 6, 8, 5, 10, 4]
puts "a = #{a}"
puts "--> #{a.rank}"
puts
puts "b = #{b}"
puts "--> #{b.rank}"
puts
puts "c = #{c}"
puts "--> #{c.rank}"
puts
puts "d = #{d}"
puts "--> #{d.rank}"