Question

I’m running a script that runs through folders and files and use these very simple loops. Now I was wondering how I could compare the current filename with the one that comes next, within this loop?

list_of_files = {}
    for (dirpath, dirnames, filenames) in os.walk(path):
        for filename in filenames:
           print 'I know here I could print: ', filename
           print 'but how could I print: ', filename+1

Generally, what I want to accomplish is to compare the two files, select one on certain criteria, compare with the next in the same folder on these criteria – until the end of the folder. In the next folder I would like to do the same again.

Answer 1

You may be able to extend this to do what you want:

>>> for a, b in zip(range(10), range(10)[1:]):
...     print a, b

like this:

for filename, next in zip(filenames, filenames[1:]):
    print filename, next

Edit: I forgot about itertools.

def pairwise(iterable):
    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
    a, b = tee(iterable)
    next(b, None)
    return izip(a, b)