Question

I was wondering if you guys had any input on how to efficiently go about doing this, I currently have a working implementation using Python’s collections class.

Answer 1

It depends on how much memory you have available (and the size of the files of course).

If you have enough memory available than I’d personally just take the easy way and create a list of all items and do a sort() on them.

Something like this:

# Read all except the first (header) lines
lines = file('1.txt').readlines()[1:]
lines += file('2.txt').readlines()[1:]

lines.sort(key=lambda x: int(x.split()[0]))

print ''.join(lines)

Alternative for the lambda:

def key(x):
    return int(x.split()[0])