Python: reading and writing multiple files

Question

import sys
import glob
import os.path

list_of_files = glob.glob('/Users/Emily/Topics/*.txt') #500 files

for file_name in list_of_files:
    print(file_name)

f= open(file_name, 'r')
lst = []
for line in f:
   line.strip()
   line = line.replace("\n" ,'')
   line = line.replace("//" , '')
   lst.append(line)
f.close()

f=open(os.path.join('/Users/Emily/UpdatedTopics',
os.path.basename(file_name)) , 'w')

for line in lst:
   f.write(line)
f.close()

I was able to read my files and do the preprocessing. The problem that I am facing is that when I write files, I can only see one file. I have to get 500 files.

Answer 1

As currently written, the only file that is being processed is the last file in the list of file names. You need to indent so that each file is processed in your loop.

import sys
import glob
import os.path

list_of_files = glob.glob('/Users/Emily/Topics/*.txt') #500 files

for file_name in list_of_files:
    print(file_name)

    # This needs to be done *inside the loop*
    f= open(file_name, 'r')
    lst = []
    for line in f:
       line.strip()
       line = line.replace("\n" ,'')
       line = line.replace("//" , '')
       lst.append(line)
    f.close()

    f=open(os.path.join('/Users/Emily/UpdatedTopics',
    os.path.basename(file_name)) , 'w')

    for line in lst:
       f.write(line)
    f.close()

Answer 2

Python uses indentation instead of curly braces to help group code. Right now, when your code is indented, Python interprets it like this:

# get list of files
list_of_files = glob.glob('/Users/Emily/Topics/*.txt') #500 files

# loop through all file names
for file_name in list_of_files:
    # print the name of file
    print(file_name)

# PROBLEM: you remove your indentation so we are no longer in
# our for loop.  Now we take the last value of file_name (or the
# last file in the list) and open it and then continue the script
f= open(file_name, 'r')
...

, for - . script , for.