Python Answer to Embedly's Challenge 2

challenge2.py

import math;
import urllib
from xml.dom import minidom

def std(n):
    return math.sqrt(sum(map(lambda x: (x - float(sum(n))/ len(n))** 2, n))/len(n))

article = minidom.parse(urllib.urlopen("http://apply.embed.ly/static/data/2.html")).getElementsByTagName("article")[0]
tags = ();

def decnt(xml,depth):
    global tags;
    for node in xml.childNodes:
        if(node.hasChildNodes):
            decnt(node,depth + 1);
        tags += ((node.nodeName,depth),);
       
decnt(article,1);

#print map(lambda x: x[1],filter(lambda x: x[0] == u'p',tags))

print std(map(lambda x: x[1],filter(lambda x: x[0] == u'p',tags)))