Weighted choice module

-- table MUST be a dictionary and have a weight entry!
local function CalculateMaxWeight(aTable)
    local result = 0

    -- add all entries weights together, to get one big value
    for _, entry in pairs(aTable) do
        result = result + entry.Weight
    end

    return result
end

return function(aWeightedTable)
    -- Choose a random number between 0 and the max weight
    local MaxWeight = CalculateMaxWeight(aWeightedTable)
    local randI = math.random(MaxWeight)

    -- iterate the entries to see wich will be choosed based on their weight
    for _, entry in pairs(aWeightedTable) do
        -- the random number is lower than the current entry weight? Tehn return me that entry IT WAS SELECTED
        if randI <= entry.Weight then
            return entry
        else -- Substract and keep rolling
            randI = randI - entry.Weight
        end
    end
end