cumulative probability, Lua

Language: Layout:

function dump (tbl, indent)
  if not indent then indent = 0 end
  local toprint = string.rep(" ", indent) .. "{\r\n"
  indent = indent + 2 
  for k, v in pairs(tbl) do
    toprint = toprint .. string.rep(" ", indent)
    if (type(k) == "number") then
      toprint = toprint .. "[" .. k .. "] = "
    elseif (type(k) == "string") then
      toprint = toprint  .. k ..  "= "   
    end
    if (type(v) == "number") then
      toprint = toprint .. v .. ",\r\n"
    elseif (type(v) == "string") then
      toprint = toprint .. "\"" .. v .. "\",\r\n"
    elseif (type(v) == "table") then
      toprint = toprint .. dump(v, indent + 2) .. ",\r\n"
    else
      toprint = toprint .. "\"" .. tostring(v) .. "\",\r\n"
    end
  end
  toprint = toprint .. string.rep(" ", indent-2) .. "}"
  return toprint
end

local items = { [1] = {id = "bandage", w = 2}, [2] = {id = "bow", w = 4}, [3] = {id = "gold", w = 1}, [4] = {id = "apple", w = 5} }

local function sorter( a, b ) return a.w < b.w end
table.sort( items, function(a, b) return a.w < b.w end)

function raffle(table)
	local total_rate = 0

for i = #table, 1, -1 do
        total_rate = total_rate + table[i].w
	end

assert(total_rate > 0)
    math.randomseed(os.time())

local c = 0 -- cumulative probability
	local randf = math.random()

for i = 1, #table do
        c = c + table[i].w / total_rate

if (randf <= c) then
            return table[i]
		end
	end
end

print(raffle(items).id)

[ + ] Show input
Absolute running time: 0.17 sec, cpu time: 0.02 sec, memory peak: 5 Mb, absolute service time: 0,31 sec