Efficient file handling in Python: Reading large text files line by line

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Handling large text files efficiently is a common challenge in programming, especially when dealing with log files, data dumps, or large datasets. Python offers a simple yet effective solution for reading such files without the need to load the entire content into memory. This guide will show you how to read a large text file line by line in Python, preserving memory and enhancing performance.

Why line-by-line reading?

Reading a file line by line is crucial when dealing with large files. It prevents memory overload by not loading the entire file content at once, making it possible to process or analyze large datasets on machines with limited memory.

This script requires Python, which is generally pre-installed on many operating systems. No additional libraries are required for this task.

Writing the Python script

The key to reading a file line by line is to use Python’s built-in file handling capabilities.

Opening the file:

Use the open function in a context manager (with statement) to ensure proper handling of file resources:

with open('large_file.txt', 'r') as file:
    for line in file:

Processing each line:

Implement a process function that defines what you want to do with each line:

def process(line):
    # Add your processing logic here

Testing the script

To test this script, you’ll need a large text file. You can create a simple text file for testing purposes with repeated lines of text. Here’s an example of how you might generate a test file:

with open('test_large_file.txt', 'w') as file:
    for i in range(1000000):  # Adjust the range for desired file size
        file.write(f"This is line {i}\n")

Run the file-reading script on this generated file to observe how it handles the file without consuming significant memory.

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Author: user