b1.py

# Code listing #11

""" Module B (b.py) - Implement functions provide some statistical methods """

# Note - this is version 1 of b, so called b1.py

import a1 as a

def rms(narray):
    """ Return root mean square of array of numbers"""

    return pow(sum(a.squares(narray)), 0.5)

def mean(array):
    """ Return mean of an array of numbers """

    return 1.0*sum(array)/len(array)

def variance(array):
    """ Return variance of an array of numbers """
    
    # Square of variation from mean
    avg = mean(array)
    array_d = [(x - avg) for x in array]
    variance = sum(a.squares(array_d))
    return variance

def standard_deviation(array):
    """ Return standard deviation of an array of numbers """
    
    # S.D is square root of variance
    return pow(variance(array), 0.5)