Lua Function Implementation

Objective

We'll create a function in Lua that processes a list of numbers and returns a table containing the mean, median, and mode of the given numbers. The code will adhere to best practices, including proper validation and documentation.

Required Libraries

Lua has a built-in table library that we will utilize for table manipulations. We won't import external libraries for this basic implementation.

Function: calculateStatistics

Documentation

--- Calculate mean, median, and mode of a list of numbers.
-- @param numbers table: A table of numbers to analyze.
-- @return table: A table containing the mean, median, and mode.
-- @raise error: Throws an error if the input is not a table or is empty.
function calculateStatistics(numbers)
  -- Input validation
  if type(numbers) ~= "table" or #numbers == 0 then
    error("Input must be a non-empty table of numbers.")
  end

  -- Initialize variables for calculations
  local sum = 0
  local frequency = {}
  
  -- Calculate mean and frequency for mode
  for _, num in ipairs(numbers) do
    if type(num) ~= "number" then
      error("All elements in the input table must be numbers.")
    end
    
    sum = sum + num
    frequency[num] = (frequency[num] or 0) + 1
  end
  
  local mean = sum / #numbers
  
  -- Calculate median
  table.sort(numbers)
  local median
  if #numbers % 2 == 0 then
    median = (numbers[#numbers / 2] + numbers[#numbers / 2 + 1]) / 2
  else
    median = numbers[math.ceil(#numbers / 2)]
  end

  -- Calculate mode
  local mode, maxCount = {}, 0
  for num, count in pairs(frequency) do
    if count > maxCount then
      mode = {num}
      maxCount = count
    elseif count == maxCount then
      table.insert(mode, num)
    end
  end
  
  return {mean = mean, median = median, mode = mode}
end

Function Breakdown

• Input Validation: The function checks if the input is a non-empty table of numbers, raising an error if conditions aren't met.
• Calculating Mean: The sum of all elements is divided by the count of numbers.
• Calculating Median: The numbers are sorted, and the median is extracted based on whether the count is odd or even.
• Calculating Mode: A frequency table is constructed to determine the most common numbers.

Example Usage

Here's how you can use the calculateStatistics function in a real-world scenario:

local numbers = {1, 2, 2, 3, 4, 4, 4, 5, 6}
local stats = calculateStatistics(numbers)

print("Mean:", stats.mean)    -- Output: Mean: 3.3333333333333
print("Median:", stats.median) -- Output: Median: 4
print("Mode:", table.concat(stats.mode, ", ")) -- Output: Mode: 4

Conclusion

This implementation provides a comprehensive way to analyze a list of numbers, calculating mean, median, and mode with robust error handling and input validation. For further knowledge on data analysis, consider exploring courses on the Enterprise DNA Platform.