percentages

Abiz

Hello,
can anyone tell me the best way to randomize something with their being a percentage of it weighted on a side?
for example my game is to shoot some zombies, and i want their being a 40/30/20/10% chance of it spawning a certain type of zombie, here is the code that i have now

local percentage = math.random ( 0, 100 )
if percentage <=40 then
-- spawn weak zombie
else if percentage >40 or percentage <=70 then
-- spawn regular zombie
else if percentage >70 or percentage <=90 then
-- spawn fast zombie
else if percentage >90 then
-- spawn brutal zombie
end

is this the best way to do it?

atilim

Hi Abiz,

IMHO, your way is pretty good and can be improved a little bit:

local percentage = math.random(0, 100) if percentage <= 40 then -- spawn weak zombie elseif percentage <= 70 then -- spawn regular zombie elseif percentage <= 90 then -- spawn fast zombie else -- spawn brutal zombie end

If you want to generalize this approach, you may use a way like this. Here spawnWeakZombie, spawnRegularZombie, spawnFastZombie and spawnBrutalZombie are functions:

local spawnList = { {ratio = 0.4, func = spawnWeakZombie}, {ratio = 0.3, func = spawnRegularZombie}, {ratio = 0.2, func = spawnFastZombie}, {ratio = 0.1, func = spawnBrutalZombie}, }   local function spawnZombie() local rnd = math.random() local sum = 0 for i = 1, #spawnList do sum = sum + spawnList[i].ratio if rnd <= sum then spawnList[i].func() return end end end

hmmmhh.. zoombiieesss..