How can I save the changes for all text files in a directory?

Question

My first aim was to replace all commas in all text files in a directory with space. (To work on them easily. I have 100 text files.)

I first took all the data as string, then applied the code below. It works. However, I am bit lack of knowledge about how to save those changes in all text files, in my actual folder.

Thank you for any help and recommendations.

The code;

from pathlib import Path
from os import listdir
from os.path import isfile, join

path = "/folder"
only_files = [f for f in listdir(path) if isfile(join(path, f))]
all_lines = []
for file_name in only_files:
    file_path = Path(path) / file_name
    with open(file_path, 'r') as f:
        file_content = f.read()
        file_content = file_content.replace(",", " ")
        all_lines.append(file_content.splitlines())
        print(file_content)

score 1 · Accepted Answer · answered Jan 24 '22 at 10:05

You close the file and open it again for writing, then overwrite it:

from pathlib import Path
from os import listdir
from os.path import isfile, join

path = "/folder"
only_files = [f for f in listdir(path) if isfile(join(path, f))]
all_lines = []
for file_name in only_files:
    file_path = Path(path) / file_name
    with open(file_path, 'r') as f:
        file_content = f.read()

    # read https://stackoverflow.com/q/123198/7505395  for better
    # ways to copy a file - this creates a backup of your current file
    with open(file_path + ".bak", "w") as bak:
        bak.write(file_content)  

    # this opens your file as new empty file and fills it 
    # with the replaced content
    with open(file_path, "w") as f:
        replaced_file_content = file_content.replace(",", " ")
        f.write(replaced_file_content)

    print(replaced_file_content)

Some editors (f.e. notepad++) allow for a "Replace over files" inside a directory or over all open editortabs - no need to code it yourself if you got that lying around. — Patrick Artner, Jan 24 '22 at 10:09

score 1 · Answer 2 · answered Jan 24 '22 at 10:10

Basically what you want to do is overwrite the same file with modified data after reading its content. Here are two ways to go about it -

# read the file data
with open(file_path, 'r') as f:
    data = f.read()

# modify the data here and generate newData
newData = data.replace(",", " ")

# write the file data, note w here for write
with open(file_path, 'w') as f:
    f.write(newData)

Here's the second way, where we open the file only once. r+ mode is meant for opening a file for both reading + writing -

with open(file_path, 'r+') as f:
    data = f.read()       # read the file content
    newData = data.replace(",", " ")
    f.seek(0)             # set the cursor to beginning of the file
    f.write(newData)      # overwrite the file with new data
    f.truncate()          # if newly written data is smaller than original data, truncate the file here

How can I save the changes for all text files in a directory?

2 Answers2