How to split string into arrays of duplicates?

Say I have a string: $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ul ! I want to split it into: { "$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$", "u", "l", " ", "!", " " } This is my current code:

local function splitIntoDuplicates(str)
	local match = str:sub(1, 1)
	local i = 2
	local j = 1
	
	local duplicates = {""}
	
	while i <= #str do
		if str:sub(i, i) == match then
			duplicates[j] ..= str:sub(i, i)
		else
			match = str:sub(i, i)
			
			j += 1
			duplicates[j] = ""
		end
		
		i += 1
	end
	
	return duplicates
end

It works for the first part, but then everything else just becomes empty strings: {                     [1] = "$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$",                     [2] = "",                     [3] = "",                     [4] = " ",                     [5] = ""                  } The code is horribly hacky in the first place. Is there a better method, perhaps with string matching?