Bulk renaming files with Python

Question

I have multiple files in various folders that look like this:

cat - dog - bark.docx

I want to bulk rename the files so that the string before the first hyphen is moved to the end of the filename:

dog - bark - cat.docx

Here’s what I’ve got so far:

import os
path = input(‘Copy and paste the location of the files.’)
for filename in os.listdir(path):
  filename_without_ext = os.path.splitext(filename)[0]
  extension = os.path.splitext(filename)[1]
  str_to_move = filename.split('-')[0]
  new_filename = filename_without_ext.split('-')[1:] + ' - '+ str_to_move + extension
  os.rename(os.path.join(path, filename), os.path.join(path, new_filename))

When I run the code it brings up the error message

‘TypeError: can only concatenate list (not "str") to list’. I’d be very grateful if someone could tell me what I’m doing wrong.

I’m new to coding and Python (as you can probably tell) so go easy on me.

My guess would be filename_without_ext.split('-')[1:] is returning a list not a single string even if its just a list of 1 element. — Ymareth, May 10 '18 at 10:45
You have file names with spaces in them, and you are renaming them in some way what that *doesn't even remove the spaces*? Needs more [detox](http://detox.sourceforge.net/). — Andrey Tyukin, May 10 '18 at 11:42

score 0 · Accepted Answer · answered May 10 '18 at 10:43

You're trying to concatenate a list with a string which does not work. Try replacing:

new_filename = filename_without_ext.split('-')[1:] + ' - '+ str_to_move + extension

with

new_filename = '-'.join(filename_without_ext.split('-')[1:]) + '-' + str_to_move + extension

score 0 · Answer 2 · answered May 10 '18 at 10:45

import os
path = input(‘Copy and paste the location of the files.’)
for filename in os.listdir(path):
  filename_without_ext = os.path.splitext(filename)[0]
  extension = os.path.splitext(filename)[1]
  parts_of_filename = filename_without_ext.split(' - ')
  new_filename = parts_of_filename[1] + ' - '+ parts_of_filename[2] + ' - ' + parts_of_filename[0] + extension
  os.rename(os.path.join(path, filename), os.path.join(path, new_filename))

score 0 · Answer 3 · answered May 10 '18 at 10:45

Your problem is this line:

new_filename = filename_without_ext.split('-')[1:] + ' - '+ str_to_move + extension

You're trying to concatenate a string to a list. The assumption you're making is that each element of the list would be added together before your next statement. The code is ambiguous as you could either want that or you could want to add your substring to each element of the list.

You want to use join as this answer said.

So:

'-'.join(filename_without_ext.split('-')[1:])

Though you still have the leading space on your first entry to worry about. So you might want to split by ' - ' instead.

Thanks! This explanation is very helpful. – Kat hughes May 10 '18 at 11:52 — Kat hughes, May 10 '18 at 11:52
No problem, glad it was helpful :) – Tim Bradley May 10 '18 at 13:14 — Tim Bradley, May 10 '18 at 13:14

Bulk renaming files with Python

3 Answers3