Function variance

pattern/metrics.py:556–563

Returns the variance of the given list of values. The variance is the average of squared deviations from the mean.

(list, sample=True)

    return s[n/2]

def variance(list, sample=True):
    """ Returns the variance of the given list of values.
        The variance is the average of squared deviations from the mean.
    """
    # Sample variance = E((xi-m)^2) / (n-1)
    # Population variance = E((xi-m)^2) / n
    m = mean(list)
    return sum((x-m)**2 for x in list) / (len(list)-int(sample) or 1)
    
def standard_deviation(list, *args, **kwargs):
    """ Returns the standard deviation of the given list of values.