Python nested loop

Question

Hello I am new to python and have a question about the best/pythonic way to do nested loops.

I want to go put each directory in an array with a nested array of the file contained in a that directory.

I have been looking at pythons arrays, dicts, sets and tupples and not sure of the best way to do this

[ Note I just want to do this for one level not recursively through all directories ]

Currently I have a function that adds all the files of sub-directories to an array, but now I need to return their parent folder too.

Thanks in advance

 def getffdirs():
 filedirs = []
 path = os.curdir
 for d in os.listdir(path): 
 if os.path.isdir(d):
 print("Entering " + d)
 curPath = os.path.join(path, d)
 for f in os.listdir(curPath): 
 if os.path.isfile(f):
 print("file " + f) 
 filedirs.append(f) 
 return filedirs

• Jeff: If you're going to use this for anything other than learning I would suggest using os.walk
• Steve Tjoa: In general, I agree, but what if you only want a single level?
• Keith: Hey @jeff As I said I was new to python, I looked at os.walk but thought it might be overkill for one directory level. Would os.walk be better ?
• S.Lott: @Keet: os.walk is the only correct solution. One level or 100 levels.
• Jeff: @Keet no it's not overkill because os.walk will return a generator object (very cool/efficient python tool) For example foo = os.walk() to get the generator object and levelOne = foo.next() for the first level list. Two lines of code... not bad.

Answer 1

i'd use a dictionary for this purpose, the keys would be directories and the values lists of files:

def getffdirs():
 dirs = {}
 path = os.curdir
 for d in os.listdir(path): 
 if os.path.isdir(d):
 print("Entering " + d)
 dirs[d] = [] # add directory with empty list
 curPath = os.path.join(path, d)
 for f in os.listdir(curPath): 
 if os.path.isfile(f):
 print("file " + f) 
 dirs[d].append(f) # add files to appropriate directory
 return dirs

to access the data:

for dir,files in dirs.items(): # notice the call to dirs.items(), thats what was missing.
 print "directory: ",dir
 print "files:"
 for f in files:
 print f

• Keith: Thank for that. That seems like what I am after but I get a 'ValueError: too many values to unpack' error. Any ideas ?

Answer 2

EDIT: If you want a dictionary,

EDIT 2: If you want to omit hidden directories,

from os import listdir, curdir
from os.path import isfile, isdir, join
filedirs = dict((d, [f for f in listdir(d) if isfile(join(d,f))]) 
 for d in listdir(curdir) if isdir(d) and d[0] != '.')

---

Original:

Is this what you're looking for?

filedirs = [[f for f in os.listdir(d) if os.path.isfile(os.path.join(d,f))]
 for d in os.listdir('.') if os.path.isdir(d)]

• Keith: Thanks for that, your original solution only returned the files as I had already, but both were interesting approaches ! I think you're right, dictionary's are the way to go.