One topic we won't have time to dive deeply in is regular expressions.

This is a shorthand syntax for pattern matching in strings. In

python, the "re" module provides support for regular expressions.

Here's an example:

import re

strings = [r"<a>this is my string</a>",

r"<b>this is a different string</b>"]

# this is the pattern that we will match -- it has 3 groups

re_test = r"<(\w*)>(.*)</(\w*)>"

for s in strings:

a = re.search(re_test, s)

if not a == None:

if a.group(1) == a.group(3):

# we found a match

print "string in '{}' tags is: {}".format(a.group(1), a.group(2))

This will find XML-like tags, <tag>this is text in the tag</tag> and

extra the text associated with each tag.

If you remove the "*" after the "\w", it will restrict itself to

single-character tags.

This webpage:

http://txt2re.com/

will help you design a regular expression for whatever type of

operation you want to do.

Games are even devised around finding complex regexs:

http://xkcd.com/1313/

(note the hover text there has a regular expression that supposedly

will correctly match all the winners of all US Presidental elections,

but not the losers) -- anyone what to try it?