Question

I’m trying to walk a directory, retrieve all files within that directory ending with a certain extension, and write that file to a list. This is list is supposed to be returned after the function is done doing its job.

def grabFiles(source,ext):
    import fnmatch
    import os

    matches = [] #tmp var which is used to return the files matching the search mask.
    for root, dirnames, filenames in os.walk(source):   #for each folder & subfolder do:
        for filename in fnmatch.filter(filenames, ext): #and for each file found like that do:
            matches.append(os.path.join(root, filename))#append the file name&directory to the "matches" variable.
    return(matches) #return the content of matches

Now when I run this using the following:

ext=[".caf", ".lmg", ".chr", ".cdf", ".dds", ".tif", ".mtl", ".cgf", ".cga"]

for filetype in ext:
     files= nPy.grabFiles("D:\\01_SVN\\01_DE\\trunk\\Game",filetype)
     print files

I believe it should be returning me a list with files for each extension in my ext list, right?
Instead it returns a [ ] for each item in the ext list.

If I fire this thing without using a definition, it works just fine :/

import fnmatch
import os
source ="D:\\01_SVN\\01_DE\\trunk\\Game"  
extension = ["*.mtl","*.tif","*.chr"] 
matches = []
for filetype in extension:
    for root, dirnames, filenames in os.walk("%s" % (source)):
        for filename in fnmatch.filter(filenames, "%s" % (filetype)):
            matches.append(os.path.join(root, filename))
print matches  

I’ve been staring at this for over an hour, and Im afraid im practically blind to my own script by now :< Im either incapable of returning a dang list, or Im misunderstanding how returning works – but it should be passing the list from matches to a new var without a problem, no?

Answer 1

I believe you are matching .ext instead of *.ext. Try adding the star to match the name and it should work.

def grabFiles(source,ext):
    import fnmatch
    import os

    matches = []
    for root, dirnames, filenames in os.walk(source):
        for filename in fnmatch.filter(filenames, '*' + ext):
            matches.append(os.path.join(root, filename))
    return matches

About you programming style:

• avoid repeating what you are doing in comments. It is useless
• return is a keyword like print, not a function
• I would use endswith rather that fnmatch.filter
• avoid importing in functions
• instead of source ="D:\\01_SVN\\01_DE\\trunk\\Game" use source=r"D:\01_SVN\01_DE\trunk\Game"