Source code for penchy.statistics

This module provides common statistical functions.

 .. moduleauthor:: Pascal Wittmann <>

 :copyright: PenchY Developers 2011-2012, see AUTHORS
 :license: MIT License, see LICENSE
from __future__ import division

import math

[docs]def average(xs): """ Average the numbers in ``xs``. :param xs: numbers to average :type xs: list of numbers :returns: averaged numbers :rtype: float """ return sum(xs) / len(xs)
[docs]def standard_deviation(xs, ddof): """ Computes the sample standard deviation of the samples ``xs``. :param xs: sample values :type xs: list of numbers :param ddof: Delta Degrees of Freedom (ddof): ``ddof`` is substracted from the divisor. :type ddof: integer :returns: sample standard deviation :rtype: float """ avg = average(xs) return math.sqrt(sum((x - avg) ** 2 for x in xs) / (len(xs) - ddof))
[docs]def coefficient_of_variation(xs): """ Computes the coefficient of variation of the samples ``xs``, i.e. the standard deviation divided by the mean. :param xs: sample values :type xs: list of numbers :returns: coefficient of variation :rtype: float """ return standard_deviation(xs, ddof=1) / average(xs)