sh, Lua - rextester

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

local total_rate = 0

for k, v in ipairs(items) do
	total_rate = total_rate + v.w
end

local rates = {}
for k, v in ipairs(items) do
	rates[#rates + 1] = {id = v.id, rate = v.w / total_rate}
end

for k = 1, #rates do
    if k == 1 then goto LABEL end
        rates[k].rate = rates[k - 1].rate + rates[k].rate
    ::LABEL::
end

print(dump(rates))

[ + ] Show input
Absolute running time: 0.19 sec, cpu time: 0.02 sec, memory peak: 5 Mb, absolute service time: 0,22 sec