#
# Produced by:
# 	Graham Thompson
#	captainhammy@gmail.com
#	www.captainhammy.com
#
# Name:         listutils.py
#
# Comments:     Perform mathematical and statistical operations on lists.
#
# Version:      1.0
#

import random

def shuffle(values):
    """Randomly shuffle the list."""
    return random.shuffle(values)


def square(values):
    """ Return the square of each value in the list. """
    return [element**2 for element in values]


def sumSquares(values):
    """ Return the sum of the squares of all values. """
    return sum(square(values))


def average(values):
    """ Return the average of the values in the list. """
    return sum(values) / float(len(values))


def median(values):
    """ Return the median value of a list. 
    
        If there is an even number of elements, it is the
        higher of the two possible values.
    """
    values.sort()
    return values[len(values) / 2.0]


def rootMeanSquare(values):
    """ Return the square root of the average of the squares
        of all values in the list.
    """
    squares = square(values)
    avg = average(squares)
    return avg ** 0.5


def standardDeviation(values):
    """ Computer the standard deviation of the values in
        the list.
    """
    mean = average(values)

    differences = [(value - mean)**2 for value in values]

    return average(differences) ** 0.5