Table.sort only works sometimes (invalid sorting function for sorting)

[SyntaxWizard]

I have a script that loops through spawnable pads and inserts them into a table. I then try to random sort the table but it’s giving me 3 2 major issues.

Here’s the code in question:

local RNG = Random.new()

local function getSpawnPads(group)
	local spawnPads = {}
	
	for _, spawnPad in ipairs(group.SpawnPads:GetChildren()) do
		if spawnPad:IsA("BasePart") then
			if not spawnPad:FindFirstChildOfClass("Decal") then
				table.insert(spawnPads, spawnPad)
			end
		end
	end
	table.sort(spawnPads, function()
		return RNG:NextNumber() < 0.5
	end)
	
	print("Successful sorting. Results:")
	print(spawnPads)
	return spawnPads
end

I don’t even know what’s causing this.

I’ve tried printing spawnPads pre-sorted and I don’t see anything wrong with it.

But it gets weirder. Sometimes, the sorting works, successfully spawning the first dummy. When it attempts it again, it will throw the same “invalid sorting function for sorting” error.

The table in the output is what the successful sorted table looks (works fine) before attempting again and erroring.

Note that these screenshots were from back to back play tests, no modified code. I’ve been at this for an hour now, I am very confused on what is causing this issue. I would appreciate any help!

Edit: Upon further testing, it seems that the code will throw an error if the function returns true

[kylerzong]

I need help with math.random

function SortRandom(Objs) local sorted = {} local Taken = {} for Index, Value in pairs(Objs) do local function Sort() local RandomSlot = math.random(1, #Objs) if Taken[RandomSlot] == nil then Taken[RandomSlot] = true sorted[RandomSlot] = Value else Sort() end end Sort() end return sorted end for _, Value in pairs(SortRandom(workspace.Folder:GetChildren())) do Value:Destroy() wait(1) end

[SyntaxWizard]

Fixed. The logic is still not clear to me but I found an answer after so many keywords:

Table sorting giving mixed outputs

If you pass a function into table.sort then the result of that comparator has to be consistent for each table element. i.e. if a < b evaluates to true then a >= b MUST evaluate to false, otherwise you will get the “invalid order function for sorting” error. This consistency can never be guaranteed if you use a comparator that returns true or false randomly.

This thread contains a lua-interpreted shuffler algorithm.