How to iterate across lines in two files simultaneously?

Question

I have two files, and I want to perform some line-wise operation across both of them. (In other words, the first lines of each file correspond, as do the second, etc.) Now,

Answer 1

You could try

for line1, line2 in zip(file1, file2):
    #do stuff

Careful though, this loop will exit when the shorter file ends.

When using Python 2, itertools.izip is better for this sort of thing because it doesn't create a list.