In python exclude folders which start with underscore or more than six characters long

Question

I want to store all the folder names except the folders which start with underscore (_) or have more than 6 characters.To get the list, i use this code

folders = [name for name in os.listdir(".") if os.path.isdir(name)]

What change do i need to make to get the desired output.

i used @dr-jimbob solution 'folders = [name for name in os.listdir(".") if os.path.isdir(name) and name[0] != '_' and len(name) <= 6]' — Kneerudge, Apr 15 '14 at 08:54
Do you mean you don't need recursive then? You should edit the question to say, because your question is ambiguous. — smci, Apr 15 '14 at 08:56

sateesh · Answer 1 · 2014-04-15T07:58:52.143

1

Another approach would be to use os.walk. This would traverse the entire directory tree from the top level directory you specify.

import os
from os.path import join
all_dirs  = []

for root,dirs,filenames in os.walk('/dir/path'):
    x = [join(root,d) for d in dirs if not d.startswith('_') and len(d)>6]
    all_dirs.extend(x)
print all_dirs # list of all directories matching the criteria

edited Apr 15 '14 at 07:58

answered Apr 15 '14 at 07:28

sateesh

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i did not try with os.walk. I'll give this a try – Kneerudge Apr 15 '14 at 08:53
Bug: exclude-condition `not d.startswith('_') and len(d)>6` should be '<=6'. `not` is taking precedence over `and`. Use parens for clarity: – smci Apr 15 '14 at 09:04
@smci why so ? OP wants * folders that doesn't start with _ and * folders that have length >6 . Boolean NOT has a higher precedence over boolean AND, so the above conditional would be fine. Though adding parentheses to disambiguate would have been better. – sateesh Apr 15 '14 at 10:32

dr jimbob · Accepted Answer · 2014-04-15T08:46:36.167

1

Well the simplest way is to extend the if clause of your list comprehension to contain two more clauses:

folders = [name for name in os.listdir(".") 
           if os.path.isdir(name) and name[0] != '_' and len(name) <= 6]

edited Apr 15 '14 at 08:46

answered Apr 15 '14 at 07:35

dr jimbob

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score 0 · Answer 3 · answered Apr 15 '14 at 07:07

A list comprehension might be too unwieldy for this, so I have expanded it to make it clear what the conditions are:

folders = []

for name in os.listdir('.'):
   if os.path.isdir(name):
      dirname = os.path.basename(name)
      if not (dirname.startswith('_') or len(dirname) > 6):
         folders.append(name)

In python exclude folders which start with underscore or more than six characters long

3 Answers3