Weighted Chance System

Resources Community Tutorials
,
#25

Got something working, here’s something that works for me if anyone needs it.

#26

I’m using 0.01 - 0.001 chances and they don’t seem to work (Nevermind, I fixed it by increasing the multipler (10) to 10000

#27

Hey! Great tutorial! Can the chances be grater than 1?

#28

Yes, sorry for the late response!

1 Like
#29

Just incase someone wants this:

function six(seven,eight,nine,ten)
	return (
		
		not seven
				
			and (
				tonumber(ten) and (ten > nine) and eight or ten
			)
			
			or (
				not ten and eight and math.random(eight)
				
				or (	
					six(
						nil, 
						nine, 
						eight, 
						six(
							seven, 
							eight 
							and (eight + ten)
							or 0, 
							next(seven, nine)
						) 
					)
				)
			)
		
	)
end

print(six{Common=100,Rare=10,Legendary=1})

i tried

6 Likes
#30

I know this is so late, but how do you actually convert the numbers from “Rarities” table to actual percentage.

#31

Decide on the rarities first. No matter what, the most common item should have a rarity of 0.

Think of it this way: math.random() produces any number between 0 and 1. This means higher rarities should be larger values, since it’s harder for the random value to be at or above it.

Work backwards. Mythic is 1% chance, so that means 99% is left. Legendary is 9% chance, so that means 90% if left. Rare is 30%, so 60% is left; that 60% is the chance of the common item.

Hope that helps!

5 Likes
#33

May I ask what the difference between the math.random and Random.new(). Im not familiar with Random.new(), I have seen it plenty just personally never used it myself!

#34

May I bug you for a question about how some games have their numbers like 0.0000045% rarity.

#35

this is the improved code, and you didn’t even format it properly

local PrizeTable = {
	Prize_1 = 0.1,
	Prize_2 = 0.6,
	Prize_3 = 0.4,
	Prize_4 = 0.2,
	Prize_5 = 0.6,
	Prize_6 = 0.8,
	Prize_7 = 0.9,
	Prize_8 = 0.3,
	Prize_9 = 0.2,
	Prize_0 = 0.1,
}

local Weight = 0

for _, Chance in ipairs(PrizeTable) do
	Weight += (Chance * 10)
end

local ranNumber = math.random(1, Weight)

Weight = 0
for Prize, Chance in ipairs(PrizeTable) do
	Weight += (Chance * 10)

	if Weight >= ranNumber then
		print(`Congrats you won {Prize}`)
		break
	end
end
1 Like
#36

In what way is this improved? All you did is replace pairs with ipairs and use the new string interpolation.

2 Likes
#37

ipairs stops yielding if it reaches a nil value, and the new string interpolation cleans the code up

1 Like
#38

Fair, but I wouldn’t really call it an improvement, more just an “alternate” if you for some reason were changing weight values to nil.

1 Like
#39

bro really just obfuscated a code sample :skull:

3 Likes
#40

i tried this but it chooses the rarity with the highest number instead of the lowest because i have it like 1/5 not in decimals
how can i fix this?

#41

use :NextInteger for non decimal, :NextNumber that include decimals

#42

How do we make it get three items in the table that are made sure arent the same value?

#43

Isn’t ipairs unable to read dictionnaries?

1 Like
#44

iirc they can operate on dictionaries; ipairs generator just returns the index and the value whilst pairs returns the key and the value

#45

idk tried with ipairs it just wasn’t really looping at all