Question

I am trying to iterate through a number .rtf files and for each file: read the file, perform some operations, and then write new files into a sub-directory as plain text files with the same name as the original file, but with .txt extensions. The problem I am having is with the file naming.

If a file is named foo.rtf, I want the new file in the subdirectory to be foo.txt. here is my code:

import glob
import os
import numpy as np


dir_path = '/Users/me/Desktop/test/'
file_suffix = '*.rtf'
output_dir = os.mkdir('sub_dir')
for item in glob.iglob(dir_path + file_suffix):
    with open(item, "r") as infile:
        reader = infile.readlines()
        matrix = []
        for row in reader:
            row = str(row)
            row = row.split()
            row = [int(value) for value in row]
            matrix.append(row)
        np_matrix = np.array(matrix)
        inv_matrix = np.transpose(np_matrix)
        new_file_name = item.replace('*.rtf', '*.txt') # i think this line is the problem?
        os.chdir(output_dir)
        with open(new_file_name, mode="w") as outfile:
            outfile.write(inv_matrix)

When I run this code, I get a Type Error:

TypeError: coercing to Unicode: need string or buffer, NoneType found

How can I fix my code to write new files into a subdirectory and change the file extensions from .rtf to .txt? Thanks for the help.

Answer 1

Instead of item.replace, check out some of the functions in the os.path module (http://docs.python.org/library/os.path.html). They’re made for splitting up and recombining parts of filenames. For instance, os.path.splitext will split a filename into a file path and a file extension.

Let’s say you have a file /tmp/foo.rtf and you want to move it to /tmp/foo.txt:

old_file = '/tmp/foo.rtf'
(file,ext) = os.path.splitext(old_file)
print 'File=%s Extension=%s' % (file,ext)
new_file = '%s%s' % (file,'.txt')
print 'New file = %s' % (new_file)

Or if you want the one line version:

old_file = '/tmp/foo.rtf'
new_file = '%s%s' % (os.path.splitext(old_file)[0],'.txt')