From: Robert Klemme <shortcutter@...>
Date: 2008-12-07T21:14:39+09:00
Subject: [ruby-core:20406] Pair methods for Array?

All,

is it just me or does someone else believe these are reasonable
methods to have in Array?  Or do they happen to exist somewhere
already?

Kind regards

robert


#!/bin/env ruby

class Array
  # these are all O(n^2)
  def all_pairs?
    (0 ... size - 1).each do |p1|
      (p1 + 1 ... size).each do |p2|
	return false unless yield self[p1], self[p2]
      end
    end
    true
  end

  def any_pair?
    (0 ... size - 1).each do |p1|
      (p1 + 1 ... size).each do |p2|
	return true if yield self[p1], self[p2]
      end
    end
    false
  end

  def no_pair?
    (0 ... size - 1).each do |p1|
      (p1 + 1 ... size).each do |p2|
	return false if yield self[p1], self[p2]
      end
    end
    true
  end
end

test = [2,4,8]

puts test.all_pairs? {|x,y| x % 2 == y % 2},
  test.any_pair? {|x,y| (x - y).abs == 4},
  test.no_pair? {|x,y| (x * y) % 3 == 0}

-- 
remember.guy do |as, often| as.you_can - without end