A question on the creation of list of lists

Jean-Michel Pichavant jeanmichel at sequans.com
Wed Apr 22 19:01:23 CEST 2015

----- Original Message -----
> From: "subhabrata banerji" <subhabrata.banerji at gmail.com>
> To: python-list at python.org
> Sent: Wednesday, 22 April, 2015 6:18:30 PM
> Subject: A question on the creation of list of lists
> Dear Group,
> I am trying to open a bunch of files from a directory and trying to
> put the results in list of lists that is to say,
> that is to say,
> I have a list of file names of a directory, I want to read each one
> of them.
> After reading each one of them, I want to put the results of each
> file in a list.
> These lists would again be inserted to create a list of lists.
> to do this I am trying to write it as follows:
> list_of_files = glob.glob('C:\Python27\*.*')
>     print list_of_files
>     list1=[]
>     list2=[]
>     list_N=[list1,list2]
>     for i,j in zip(list_of_files,list_N):
>         print i,j
>         x1=open(i,"r").read()
>         x2=j.append(x1)
>     all_sent=list_N
>     print all_sent
> Am I doing anything wrong? If any one may kindly suggest?
> Is there any smarter way to do it? I am using Python2.7+
> on MS-Windows 7 Professional Edition.
> Apology for any indentation error.
> Regards,
> Subhabrata Banerjee.

I'm not sure about what you're trying to do. But here are a couple of remarks:

1/ Your file pattern search will not get files that do not have any dot in their name or will get directory that have a dot in their name. Here's a better way of filtering files:

import glob
import os

filenames = [item for item in glob.glob('C:\Python27\*') if os.path.isfile(item)]

2/ the append method returns always None

x2=j.append(x1) will bind x2 to None. That is probably something you don't want. However you never use x2, so you can simply write:


3/ your for loop seems broken, but I'm not sure as I don't really know what you're trying to do. Here's a simple code that you may start from:

filenames = [item for item in glob.glob('C:\Python27\*') if os.path.isfile(item)]
content = []
for filename in filenames:
  with open(filename, 'r') as f:

all_sent = [filenames, content] 

You should end up with a list of list, the first list is the file names, the second their content:

with 2 files file1 file2 you should get
all_sent : [['file1', 'file2'], [content1, content2]]

Is it what you're trying to do ?



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