Scraping urls from html, save in csv using BeautifulSoup - python-2.7

Question

I'm trying to save all hyperlinked urls in an online forum in a CSV file, for a research project.
When I 'print' the html scraping result it seems to be working fine, in the sense that it prints all the urls I want, but I'm unable to write these to separate rows in the CSV.
I'm clearly doing something wrong, but I don't know what! So any help will be greatly appreciated.
Here's the code I've written:
import urllib2
from bs4 import BeautifulSoup
import csv
import re
soup = BeautifulSoup(urllib2.urlopen('http://forum.sex141.com/eforum/forumdisplay.php? fid=28&page=5').read())
urls = []
for url in soup.find_all('a', href=re.compile('viewthread.php')):
print url['href']
csvfile = open('Ss141.csv', 'wb')
writer = csv.writer(csvfile)
for url in zip(urls):
writer.writerow([url])
csvfile.close()

Answer 1

You do need to add your matches to the urls list:
for url in soup.find_all('a', href=re.compile('viewthread.php')):
print url['href']
urls.append(url)
and you don't need to use zip() here.
Best just write your urls as you find them, instead of collecting them in a list first:
soup = BeautifulSoup(urllib2.urlopen('http://forum.sex141.com/eforum/forumdisplay.php?fid=28&page=5').read())
with open('Ss141.csv', 'wb') as csvfile:
writer = csv.writer(csvfile)
for url in soup.find_all('a', href=re.compile('viewthread.php')):
writer.writerow([url['href']])
The with statement will close the file object for you when the block is done.