Lua implementation of Fisher-Yates Shuffle "inside-out"

shuffle.lua

-- Remember to seed outside the function i.e. at top of your script
-- especially on OSX otherwise you will get the same permutations.
-- math.randomseed(os.time())
-- More info http://lua-users.org/wiki/MathLibraryTutorial

function random(min, max)
	if (max == null) then
		max = min
		min = 0
	end

	return min + math.floor(math.random() * (max - min + 1))
end

function shuffle(list)
  local shuffled = {}
  local len = 0

  for k, v in pairs(list) do
	j = random(0, len)

	if j == len then
		table.insert(shuffled, v)
	else
		table.insert(shuffled, shuffled[j + 1])
		shuffled[j + 1] = v
	end

	len = len + 1
  end

  return shuffled
end