# frozen_string_literal: true # # Copyright (C) 2013 - present Instructure, Inc. # # This file is part of Canvas. # # Canvas is free software: you can redistribute it and/or modify it under # the terms of the GNU Affero General Public License as published by the Free # Software Foundation, version 3 of the License. # # Canvas is distributed in the hope that it will be useful, but WITHOUT ANY # WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR # A PARTICULAR PURPOSE. See the GNU Affero General Public License for more # details. # # You should have received a copy of the GNU Affero General Public License along # with this program. If not, see . module SimpleStats def variance(items, type = :population) return 0 if items.size < 2 divisor = type == :population ? items.length : items.length - 1 mean = items.sum / items.length.to_f sum = items.map{ |item| (item - mean) ** 2 }.sum (sum / divisor).to_f end module_function :variance end