Mean, Standard deviation and Skewness functions

skew.py

import sys
import math

myvalues = [-3, -2, -1, -1, 0, 1, 2, 3, 7]


def moy(l):
    sommeval = reduce(lambda somme, val: somme+val, l, 0)
    return (float(sommeval)/len(l))

def stddev(l):
    mu = moy(l)
    n = len(l)
    cur_est = 0
    for x in l:
        cur_est += (float(x)-mu)*(float(x)-mu)
    return (float(cur_est)/(n-1))

def skew(l):
    mu = moy(l)
    sigma = math.sqrt(stddev(l))
    n = len(l)
    cur_est = 0
    for x in l:
        cur_est += ((float(x)-mu)/sigma)**3
    return (cur_est*n)/((n-1)*(n-2))

sys.stdout.write("%f %f\n"%(skew(myvalues), moy(myvalues)))