This is my example code to rename a file name with reference with a "csv" file.This csv file has a old name of a file in row[0],and new names in a row1 like this image

import csv
import os
    with open('New_Names_DDP.csv') as csvfile:
         reader = csv.reader(csvfile)
         for row in reader:
             oldname = row[0]
             newname = row[1]
             os.rename(oldname, newname)

But here i have a files with different extenstions like(.wav,.txt,.xml,.html).So I want to rename only file name with new name and add their extension automatically.Can you please help me for this.

I don't know exactly what you are trying to do, because your problem and your code sample are talking about something else.

I assume what you want is:

1. Read all the files in some directory from the hard disk.
2. If the filename (without extension) is in column a, then rename it to whatever is in column b.

To do that:

import os
import csv
import glob

file_path = '/home/foo/bar/some/where/'
file_pattrn = '*.*'
file_names = {}

with open('somefile.csv') as f:
    reader = csv.reader(f)
    for row in reader:
       file_names[row[0]] = row[1]

for file in glob.iglob(file_path+file_pattrn):
    path, filename = os.path.split(file)
    filename_noext, ext = os.path.splitext(filename)
    new_filename = file_names.get(filename_noext, filename_noext)
    os.rename(os.path.join(path, filename),
              os.path.join(path, '{}{}'.format(new_filename, ext)))

more