Core Python Programming (2nd Edition)

and split each line up into words, and we can sum up the number of words to get a total like this:
>>> f = open('hhga.txt', 'r')
>>> len([word for line in f for word in line.split()])
91
Let us get a quick total file size:
import os
>>> os.stat('hhga.txt').st_size
499L
Assuming that there is at least one whitespace character in the file, we know that there are fewer than
499 non-whitespace characters in the file. We can sum up the length of each word to arrive at our total:
>>> f.seek(0)
>>> sum([len(word) for line in f for word in line.split()])
408
Note we have to rewind back to the beginning of the file each time through because the iterator
exhausts it. But wow, a non-obfuscated one-liner now does something that used to take many lines of
code to accomplish!
As you can see, list comps support multiple nested for loops and more than one if clause. The full
syntax can be found in the official documentation. You can also read more about list comprehensions in
PEP 202.