Weighted Table not working correctly

Help and Feedback Scripting Support
#1

Problem: Weighted system does not return the correct item in range properly

Scenario:
I have a weighted table system where if the randomised number is within the range of the counter then it will return the item’s name, however some items let says in this case, a common item can still be returned even though the randomised number is like “40” which should return a rare item

Here are some examples of what i mean:

image --See how it returns a “Roffy” item ? even though the randomising value was 40 which in this case is within the range of a rare item as shown in the items table module:

local WeightedChance = { --The numbers applied to it are the chances, 125 common, 50 is rare, 3 is super rare
	Items = {
		["Rohklea"] = 125,
		["Kahruto(Kid)"] = 125,
		["Roffy"] = 125,
		["Ikigoh"] = 125,
		["Kokyu"] = 125,
		["Yuru"] = 125,
		["Zakuse(Kid)"] = 125,
		["Picohloh"] = 125,
		["Vegehtah"] = 125,
		["Chah"] = 125,
		["Kahruto(TS)"] = 50,
		["Zakuse(TS)"] = 50,
		["Vegehtah(SSJ)"] = 50,
		["Ace"] = 3,

	}

}

This is the code i use:

function RandomiseItem(TotalWeight, Stats) --Receives the total chances (This function decides the weighted system)
	local Counter = 0
	--local RarityGroup
	local Randomising = math.random(1,TotalWeight)
	for CharName, CharChances in pairs(Module.GetMainBanner()) do
		--local RarityChance = CharChances --CharChances.Rarity.Chance
		Counter = Counter + CharChances
		if Randomising <= Counter then
			--RarityGroup = CharName
			--print(RarityGroup)
			local UnlockedItems = CharName --Chances.Items
			print(Counter)
			print(Randomising)
			print(UnlockedItems)
			return UnlockedItems
		end
	end
end

Module.GetMainBanner() returns a live module consisting of the items available in the “Shop”
–Here is the screenshot
image -See how i printed it here ?

And finally!

This is where i call the RandomiseItem function

	local MainBanner = Module.GetMainBanner() --getting the banner as shown in picture above
	for Name, Chance in pairs(MainBanner) do
		TotalMainBannerWeight = TotalMainBannerWeight + Chance --Adding the total chances
	end
	coroutine.resume(coroutine.create(function()
		local Characters = RandomiseItem(TotalMainBannerWeight) --Sending the chances
	end))

Please, i appreciate if anyone can help or could show me a better way of doing it, Thank You

#2

Isnt this supposed to be in code review then?

#3

I dont think it is i explained the problem with it at the top

#4

I have made the issue more clear now Thank You

#6

There is no reason to move this to code review, this would fall under the scripting support category too.

#7

Answered on disc

function module.NormalBanner()
    return    {
        Common = {
            Chance = 125,
            Items = {
                "Rohklea",
                "Kahruto(Kid)",
                "Roffy",
                "Ikigoh",
                "Kokyu",
                "Yuru",
                "Zakuse(Kid)",
                "Picohloh",
                "Vegehtah",
                "Chah",
            }

        },

        Rare = {
            Chance = 50,
            Items = {
                "Kahruto(TS)",
                "Zakuse(TS)",
                "Vegehtah(SSJ)",
            }
        },

        SuperRare = {
            Chance = 3,
            Items = {
                "Ace",
            }
        }
    }
end

local function shallowCloneArray(tbl) -- the other function
  return {unpack(tbl)}
end

function module.getUniqueRandom(type, amount) 
    local picked = {}
    local banners = shallowCloneArray(module.GetTableType(type))
    
    for i = 1, amount do
      picked[i] = table.remove(banners, math.random(#banners))
    end
  
    return picked
end

function module.StartRandomBanner() 
    local pickedCommon = module.getUniqueRandom("common", 3)
    local pickedRare = module.getUniqueRandom("rare", 2)
    local pickedLegendary = module.getUniqueRandom("legendary",  1)

     module.UpdateMainBanner({common = pickedCommon, rare = pickedRare, legendary =  pickedLegendary }) 
end

local function getChance(type)
  return banners[type].Chance
end

local function pickItem(tbl)
  local randWeight = math.random(125 * 3 + 50 * 2 + 3) -- you can leave like this or make it function which actually calcs that
  
  for type, items in pairs(tbl) do
      for _, item in ipairs(items) do
        local chance = getChance(type)

        if randWeight <= chance then
           return item
        else
          randWeight -= chance
        end
      end
  end
end

function module.updateMainBanner(tbl)
   local pickedItem = pickItem(tbl)
   -- ... other stuff
end