How does one rename multiple files using python?

Question

I have lots of programming experience but this is my first python script. I am trying to add the prefix "00" to all the files in a specific folder. First I read the names of all the files and save them in an array. Then I sort through the array and add the prefix "00" then use the os.rename function but somewhere along the way I've messed up something.

import sys, os

file_list = []

for file in os.listdir(sys.argv[1]):
    file_list.append(file)

 for i in file_list:
    file_list[i] = prevName
    newName = '00' + file_list[i]
    os.rename(prevName, newName)

I have a .py file in the folder with all the files I want to rename. The .py file contains the script above. When i double click the .py file a cmd window flashes and disappears and none of the file names have been changed. Any help would be appreciated, sorry if this is a very obvious mistake, my python level is quite n00b at the moment.

First of all, run python from console, rather than double-clicking it, so that you can see what exception is it throwing. — Vikas Ojha
– Vikas Ojha, Commented Jun 7, 2015 at 18:34

Vikas Ojha · Accepted Answer · 2015-06-07 19:04:04Z

3

In addition to the answer by @Padraic, also make following changes to your code.

import sys, os

file_list = []

for f in os.listdir(sys.argv[1]):
    file_list.append(f)

for i in range(len(file_list)):
    prevName = file_list[i]
    if prevName != 'stackoverflow.py':  # Mention .py file so that it doesnt get renamed
        newName = '00' + file_list[i]
        os.rename(prevName, newName)

edited Jun 7, 2015 at 19:04

answered Jun 7, 2015 at 18:41

Vikas Ojha

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2 Comments

ErrorMaster Over a year ago

thank you both very much, using both of your suggestions the script ran perfectly

Padraic Cunningham Over a year ago

@ErrorMaster, you don't need to create any lists, you need os.listdir and nothing else, you also need to join the path to the file if you plan on passing in a directory name

DeepSpace · Accepted Answer · 2015-06-07 18:39:38Z

1

Check your indentation. The second for loop is not indented correctly.
for i in file_list: file_list[i] = prevName

You are not iterating correctly. for loops in Python are like foreach loops you may know from other programming languages. i in for i in file_list actually gives you the list's elements, so you should be doing for i in range(len(file_list)): file_list[i] = ......

although it is not very pythonic nor generally a good idea to modify the collection that you're currently iterating over.

answered Jun 7, 2015 at 18:39

DeepSpace

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Comments

Padraic Cunningham · Accepted Answer · 2015-06-07 18:49:29Z

1

Your code errors because you provide no args so sys.argv[1] would give an IndexError, you would need to call the script with the dir name from a cmd prompt not double click it:

python your_script directory <- argv[1]

Or change the code and specify the path, you also need to join the path to the filename.

path = "full_path"
for f in os.listdir(path):
    curr,new = os.path.join(path,f), os.path.join(path,"00{}".format(f))
    os.rename(curr,new)

os.listdir returns a list so just iterate over that, you don't need to create a list and append to it.

for i in file_list: would also make each i a filename not an index so that would cause another error but as above you don't need to do it anyway.

edited Jun 7, 2015 at 18:49

answered Jun 7, 2015 at 18:37

Padraic Cunningham

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