How would I make a rarity / chance system?

[MarsterMikkel]

So I’m making a game kinda like SCP 3008. And I’m trying to make a rarity system on the different rooms. Example: Bedroom’s chance of spawning = 5% and Cafeteria’s chance of spawning = 1%.

I have tried to make this using a Table. The given numbers are the chance they have to spawn.

local Rooms = {
	"AppartmentModel" == 5; -- Chance for it to spawn
	"BathRoom1" == 5;
	"BedRoom" == 5;
	"BedRooms" == 5;
	"Beds" == 5;
	"Carpets" == 5;
	"ChildrensRoom" == 4;
	"Coutches" == 5;
	"Kitchen" == 3;
	"Kitchen 2" == 3;
	"Kitchen3" == 2;	
	"LivingRoom" == 5;
	"MasterBedRoom" == 4;
	"Moving" == 5;
	"Office1" == 5;
	"Outdoors" == 4;
	"Pellets" == 2;
	"Storage" == 1;
	"Tables" == 5;
	"TeenRoom" == 5;
	"TwinBedroom" == 5;
}

Currently, my system just picks a random room and I don’t like that as I want to be able to make rare rooms with special game objects.

local rooms = game.ReplicatedStorage.RoomsClean:GetChildren()
local randomroom = rooms[math.random(1, #rooms)]:Clone()

If anyone out there has any idea of how I could make this “spawn chance” system please reply.

[Orbular3]

This can be answered in a simple google search: How to make a random loot table - YouTube

[MarsterMikkel]

Yeah but he doesn’t use a table to do it. Wait my bad he does

[MarsterMikkel]

Doesnt work with what im trying to do.

function GetRandomItem()
	local Sum = 0
	for RoomName,Chance in pairs(RoomsChances) do
		Sum += Chance
	end
	local RandomNumber = math.random(Sum)
	for RoomName,Chance in pairs(RoomsChances) do
		if RandomNumber <- Chance then
			return RoomName -- Error from here
                else
                       RandomNumber -= Chance
		end
	end
end

It gives me. Argument 1 missing or nil

[tlr22 (FusionOak)]

You have a typo

function GetRandomItem()
	local Sum = 0
	for RoomName,Chance in pairs(RoomsChances) do
		Sum += Chance
	end
	local RandomNumber = math.random(Sum)
	for RoomName,Chance in pairs(RoomsChances) do
		if RandomNumber <= Chance then
			return RoomName -- Error from here
        else
            RandomNumber -= Chance
		end
	end
end

It is also worth noting that since the values don’t change you only have to calculate sum once.

local Sum = 0
for RoomName,Chance in pairs(RoomsChances) do
	Sum += Chance
end

function GetRandomItem()
	local RandomNumber = math.random(Sum)
	for RoomName,Chance in pairs(RoomsChances) do
		if RandomNumber <= Chance then
			return RoomName -- Error from here
        else
            RandomNumber -= Chance
		end
	end
end

But you probably won’t actually see the performance improvement with how slight it is. Making it practically useless.

[Orbular3]

You wrote <- instead of <= - as @tlr22 said you made a typo

[un1ND3X (ice)]

A search often helps:

Selecting Value from Table

Technically the more instances of x you add to an array, the chance for getting x increases, as x/n (the probability of getting it) increases (with x/n ^ t decreasing, the probability of getting it again in a row, t times) , For instance if you want more chances of getting “Orc” from the array , you could add more instances of “Orc” in the array, like : {“goblin”,“goblin”,“goblin”,“goblin”,“human”} would cause “goblin” to technically be the most common, but it depends on how you exactly se…

Need help with this chance system

Try using NumberRanges : Selecting Value from Table Or, replace that with -- the if part of your if statement leaderstats[i].Value = leaderstats[i].Value + 1 return end adding a return.

[MarsterMikkel]

Thanks this fixed the problem cant thank you enough!