Python: simple batch rename files in windows folder

Question

Trying to create a simple code, to batch rename a folder in windows.

Musts:

• change every number , like "file02.txt", turn 02 into 0002

• maybe work for every file format, like jpg, png, txt, docx and so on (becuse I'm not sure what will be in the folder, this code might be used for image sequences...)

Is this possible?

I did test versions, combination of the little knowledge I have, but it gets me confused.

my code so far:

import os
import sys


folder_path = os.listdir(raw_input("Insert folder path: "))
print "Files in folder: %s" % folder_path

# a split tool
def mysplit(s):
    head = s.rstrip('0123456789')
    tail = s[len(head):]
    return head, tail

# a function to make a new name with needed 0000
def new_filename(filename):
    file_name_part, ext = os.path.splitext(filename) #  file01 and .ext

    original_name, number = mysplit(file_name_part) # 01 and file
    add_zero = number.rjust(4, "0") # add 0001

new_name = original_name + add_zero + ext

print new_name
    # new_name  comes like this ['file0001.txt'] but seperate, not in a list? Why?



for current_file_n in folder_path:
    new = new_filename(current_file_n)
    print list([new]) # trying to make the str into a list....


re_name = os.renames(current_file_n, new)
print re_name
print "Renamed files: %s" % folder_path

The desired outcome is the same as the beginning list, but collated with zeros,like this: ['file0001.txt', 'file0002.txt', 'file0003.txt'......'file0015.txt']

I've got errors like windows error: can't find file, and another error; can't connect str and list?

I need an explanation of what I'm doing wrong as simple as possible, or is there another method that I can use that will give me the desired outcome?

Answer 1

Your code can be simplified a lot by using regular expression substitution. re.sub() can take a replacement function. In this case adding leading zeroes to the first number found in the filename.

import os, re

def renumber_files(directory, zeroes=4):
    os.chdir(directory)
    for filename in os.listdir(directory):
        new_name = re.sub(r'\d+', lambda m: m.group().zfill(zeroes), filename, count=1)
        os.rename(filename, new_name)


renumber_files(raw_input("Insert folder path: "))

This works because re.sub() can take a callable as the replacement argument.

Signature: re.sub(pattern, repl, string, count=0, flags=0) 

Return the string obtained by replacing the leftmost non-overlapping occurrences of the pattern in string by the replacement repl. repl can be either a string or a callable; if a string, backslash escapes in it are processed. If it is a callable, it's passed the match object and must return a replacement string to be used.

In the lambda m.group() returns a string matching the pattern \d+. For instance "1", "564645" or "005".

The next step, str.zfill(4), turns those into "0001", "564645", or "0005".

Answer 2

As martineau said your indentation is messed up.

Here's the working code:

import os
import sys

# a split tool
def mysplit(s):
    head = s.rstrip('0123456789')
    tail = s[len(head):]
    return head, tail

# a function to make a new name with needed 0000
def new_filename(filename):
    file_name_part, ext = os.path.splitext(filename) #  file01 and .ext

    original_name, number = mysplit(file_name_part) # 01 and file
    add_zero = number.rjust(4, "0") # add 0001

    new_name = original_name + add_zero + ext

    return new_name
    # new_name  comes like this ['file0001.txt'] but seperate, not in a list? Why?

if __name__ == '__main__':
     folder_path = os.listdir(raw_input("Insert folder path: "))
     print "Files in folder: %s" % folder_path
     renamed_files = [] 
     for current_file_n in folder_path:
          new = new_filename(current_file_n)
          renamed_files.append(new) # Add renamed file's name to a list
          try:
               os.renames(current_file_n, new) #It doesn't return anything
               print new
          except:
               print "Unexpected error while renaming %s:%s"%(new, sys.exc_info()[0])
     print "Renamed files: %s" % renamed_files

Hope this helps