Detecting a duplicate variable

[DiamondDrencher1 (nil)]

I’ll keep this short.

Let’s say you have a table with variables:

local t = {"a","a","b","c")

Is there a way to detect if there’s two or more identical variables, and then remove them? In this example, there’s 2 a variables in this table.

If you have any suggestions or solutions, please comment them down below. Thank you.

[overflowed]

local function ClearDuplicates(t: {any})
	local Auxiliary = {}
	for _, v in t do
		Auxiliary[v] = true
	end
	table.clear(t)
	for v in Auxiliary do
		table.insert(t, v)
	end
end

local d = {"a", "a", "b", "c", "b", "d", "x", "y", "z", "z"}

ClearDuplicates(d)

print(d)

[legs_v (legs)]

You could use table.find to search for the same value and check its not the same index you’re checking from. For example

local function detectDuplicate(t, index)
  local value = t[index]
  local resultIndex = table.find(t, value)
  if resultIndex == index then
    local resultIndex = table.find(t, value, index+1)
    if resultIndex then
      return resultIndex 
    end
  else
    return resultIndex 
  end
end

local t = {"a","a","b","c")

detectDuplicate(t, 1) -- 2 (put the index of the value you wanna search)
detectDuplicate(t, 2) -- 1

doesn’t work with dictionaries btw.

Also this only detects one other duplicate and returns the index of that duplicate, so you would have to repeat the function until it returns nil if you wanna remove all duplicates.

[DiamondDrencher1 (nil)]

You have to insert the index though, I want it to search through all variables and then see which ones are identical to another.

[legs_v (legs)]

Uh if you want to remove duplicates entirely you could probably use @overflowed 's solution otherwise mine is just for checking lol.

This function will just return an array of index with duplicate values. (It doesn’t count the first instance of a value as a duplicate ofc)

local function getDuplicateTable(t)
	local duplicateTable = {} -- table full of duplicates
	for index, value in t do
		if table.find(duplicateTable, index) then continue end
		local resultIndex = table.find(t, value)
		while resultIndex do
			if resultIndex ~= index then
				table.insert(duplicateTable, resultIndex)
			end
			resultIndex = table.find(t, value, resultIndex+1)
		end
	end
	return duplicateTable
end

local t = {"a","a","b","c", "c"}
local duplicateTable = getDuplicateTable(t)
print('{'..table.concat(duplicateTable, ', ')..'}') -- {2, 5}

-- removing the duplicates
for _, i in duplicateTable do
  t[i] = nil
end