| # Copyright 2017 The Chromium OS Authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| from math import ceil, floor, sqrt |
| |
| |
| def get_kth_percentile(num_list, k): |
| """ |
| Computes the k-th percentile of a list of numbers. |
| |
| @param num_list: list with numbers. |
| @param k: the percentile to be computed. |
| |
| @returns the kth percentile value of the list. |
| |
| """ |
| if not num_list: |
| return 0 |
| assert k >= 0 and k <= 1 |
| i = k * (len(num_list) - 1) |
| c, f = int(ceil(i)), int(floor(i)) |
| if c == f: |
| return num_list[c] |
| return round((i - f) * num_list[c] + (c - i) * num_list[f], 2) |
| |
| |
| def get_median(num_list): |
| """ |
| Computes the median of a list of numbers. |
| |
| @param num_list: a list with numbers. |
| |
| @returns the median value of the numbers. |
| |
| """ |
| if not num_list: |
| return 0 |
| num_list.sort() |
| size = len(num_list) |
| if size % 2 != 0: |
| return num_list[size / 2] |
| return round((num_list[size / 2] + num_list[size / 2 - 1]) / 2.0, 2) |
| |
| |
| def get_average(num_list): |
| """ |
| Computes mean of a list of numbers. |
| |
| @param num_list: a list with numbers. |
| |
| @returns the average value computed from the list of numbers. |
| |
| """ |
| if not num_list: |
| return 0 |
| return round(float(sum(num_list)) / len(num_list) , 2) |
| |
| |
| def get_std_dev(num_list): |
| """ |
| Computes standard deviation of a list of numbers. |
| |
| @param num_list: a list with numbers. |
| |
| @returns Standard deviation computed from the list of numbers. |
| |
| """ |
| n = len(num_list) |
| if not num_list or n == 1: |
| return 0 |
| mean = float(sum(num_list)) / n |
| variance = sum([(elem - mean) ** 2 for elem in num_list]) / (n -1) |
| return round(sqrt(variance), 2) |
