Detailed explanation of 5 ways to write multiple files at the same time in Python

In actual development, some students often ask Teacher Tian Xin the scenario where data needs to be written into multiple files at the same time, such as log backup, data distribution, etc. Python provides multiple efficient and secure ways to achieve this requirement. In this article, Teacher Tian Xin will introduce 5 different methods in detail, and attach a code example and a comparison of the advantages and disadvantages of the methods.

‌1. Applicable scenarios for writing multiple files at the same time

‌Data backup‌: Save to local files and cloud storage at the same time. ‌

Logging: Output logs to the console and files at the same time.

Data conversion: Write processing results to files of different formats (such as .txt and .csv).

2. Five methods and advantages and disadvantages

2.1 Using multiple with statements nested

Applicable scenarios: The number of files is small and fixed.

# Write two files at the same timewith open('', 'w') as f1, open('', 'w') as f2:
    data = "Hello, World!"
    (data)
    (data)

Advantages: Concise code, automatic management of file closure.

‌Disadvantages‌: When there are too many files, you need to add them manually, which is not flexible enough.

2.2 Looping through the file object list

‌Applicable scenarios‌: The number of files is known and unified operations are required.

filenames = ['', '', '']
files = [open(fname, 'w') for fname in filenames]

​​​​​​​try:
    for line in ["Line 1", "Line 2"]:
        for f in files:
            (line + '\n')
finally:
    # Make sure all files are closed    for f in files:
        ()

‌Advantages‌: Suitable for dynamically generating file names.

‌Disadvantages‌: The file needs to be closed manually, and exception handling is not elegant enough.

2.3 Use Management Context

‌Applicable scenarios‌: Dynamically manage multiple files, supported by Python 3.3+.

from contextlib import ExitStack

filenames = ['', '', '']

​​​​​​​with ExitStack() as stack:
    # Batch into context and automatically manage resources    files = [stack.enter_context(open(fname, 'w')) for fname in filenames]
    for line in ["Data1", "Data2"]:
        for f in files:
            (f"{line}\n")

Advantages: Automatically handle file closure and flexible support for a large number of files.

‌Disadvantages‌: Only available for Python 3.3 and above.

2.4 Encapsulate multi-file write function

‌Applicable scenarios‌: When multiplexing the write logic.

def write_to_files(data, filenames):
    with ExitStack() as stack:
        files = [stack.enter_context(open(fname, 'w')) for fname in filenames]
        for line in data:
            for f in files:
                (line + '\n')

# Call examplewrite_to_files(["Hello", "CSDN"], ['', ''])

2.5 Multithreaded Write (Advanced Usage)

Applicable scenarios: IO-intensive tasks, writing speed needs to be improved.

import threading

def write_file(filename, content):
    with open(filename, 'w') as f:
        (content)

threads = []
data = "Multi-threaded data"
for fname in ['', '']:
    t = (target=write_file, args=(fname, data))
    (t)
    ()

# Wait for all threads to completefor t in threads:
    ()

Note: thread safety needs to be handled to avoid race conditions.

3. Frequently Asked Questions and Solutions

‌1. File permission issues‌

Make sure the program has permission to write to the target directory, otherwise a PermissionError will be thrown.

2‌. Inconsistent encoding results in error‌

Specify the unified encoding format: open(fname, 'w', encoding='utf-8').

3‌. Incomplete writing content‌

Use() to force refresh the buffer, or make sure the file is closed correctly.

4. Summary

This is the end of this article about the 5 methods of writing multiple files in Python at the same time. For more related Python to write multiple files at the same time, please search for my previous articles or continue browsing the related articles below. I hope everyone will support me in the future!