Python: os.chdir() not working within a for loop?

Question

I'm trying to get a homemade path navigation function working - basically I need to go through one folder, and explore every folder within it, running a function within each folder.

I reach a problem when I try to change directories within a for loop. I've got this "findDirectories" function:

def findDirectories(list):
    for files in os.listdir("."):
        print (files)
        list.append(files)
        os.chdir("y")

That last line causes the problems. If I remove it, the function just compiles a list with all the folders in that folder. Unfortunately, this means I have to run this each time I go down a folder, I can't just run the whole thing once. I've specified the folder "y" as that's a real folder, but the program crashes upon opening even with that. Doing os.chdir("y") outside of the for loop has no issues at all.

I'm new to Python, but not to programming in general. How can I get this to work, or is there a better way? The final result I need is running a Function on each single "*Response.xml" file that exists within this folder, no matter how deeply nested it is.

What do you mean by "the program crashes"? Probably you get some error message? — sth, Dec 12 '11 at 00:31
What do you Actually want to do? As noted in one answer, just changing to 'y' each time won't work, as you acknowledge. — Andrew Jaffe, Dec 12 '11 at 00:44

donkopotamus · Answer 1 · 2011-12-12T01:13:26.327

Well, you don't post the traceback of the actual error but clearly it doesn't work as you have specified y as a relative path.

Thus it may be able to change to y in the first iteration of the loop, but in the second it will be trying to change to a subdirectory of y that is also called y

Which you probably do not have.

You want to be doing something like

import os

for dirName, subDirs, fileNames in os.walk(rootPath):
    # its not clear which files you want, I assume anything that ends with Response.xml?
    for f in fileNames:
        if f.endswith("Response.xml"):
            # this is the path you will want to use
            filePath = os.path.join(dirName, f)

            # now do something with it!
            doSomethingWithFilePath(filePath)

Thats untested, but you have the idea ...

Brigand · Accepted Answer · 2011-12-12T00:46:56.247

1

As Dan said, os.walk would be better. See the example there.

edited Dec 12 '11 at 00:46

answered Dec 12 '11 at 00:28

Brigand

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I was just using "y" as an example because that would definitely work. I'm not assuming every folder is called "y", but rather I'd be using something like os.chdir(files). I'll take a look at os.walk, thanks. – morgoe Dec 12 '11 at 00:39

Python: os.chdir() not working within a for loop?

2 Answers2