Finding the standard deviation in python

[sick vapor]

Hello,
I'm fairly new to python and I've currently run into a road block in this problem. I set up this code:

def average(the_list):
    return the average of the list
def deltalist(the_list,a):
    return a list which is each of the element of the_list subtracted by a
def squarelist(lst):
    return a list which is each of the element of the_list squared
def variance(the_list,mean):
    return squarelist(deltalist(the_list,mean))
def stddev(l):
    a = average(l)
    l3 = variance(l,a)
    return math.sqrt(sum(l3)/(len(l3) - 1))
lst = [1,3,4,6,9,19]
print(stddev(lst))

the return statements is the problem I've ran into. I want to implement the average, squarelist, and the delta list to find the standard deviation of the list that I've used in this code. How do I use the numbers that I have listed in lst to get standard deviation?

[TrustyTony]

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[sick vapor]

This is my work as the only thing that was provided was the numbers that I listed, but I will try to complete the code to the best of my knowledge as I don't yet get the full understanding of the return statements and arguments that follow. Thanks for the response.

[TrustyTony]

This is tougher, if you do not understand fully list comprehensions, but I recommend to learn them. Here is list comprehension version

def squarelist(the_list):
    return [element**2 for element in the_list] # a list with element squared for each of the element in the_list

[Lardmeister]

You might want to take one look at:
http://www.daniweb.com/software-development/python/threads/20774/starting-python/9#post796257

[sick vapor]

This is what I compiled:

import math

q = [1,3,4,6,9,19]
avg = float(sum(q))/len(q)
print(avg)
dev = []
for x in q:
    dev.append(x - avg)
print(dev)
sqr = []
for x in dev:
    sqr.append(x * x)
print(sqr)
mean = sum(sqr)/len(sqr)
print(mean)
standard_dev = math.sqrt(sum(sqr)/(len(sqr)-1))
print("the standard deviation of set %s is %f" % (q, standard_dev) )

thanks for your guys help.