How Can I Elegantly Concatenate Text Files in Python?

An Elegant Solution for Concatenating Text Files in Python

When dealing with multiple text files, the need to concatenate them into a single file often arises. While using the line-by-line approach with open(), readline(), and write() methods may seem straightforward, it lacks elegance.

Python offers more sophisticated methods for this task. Consider the following approaches:

For Large Files:

filenames = ['file1.txt', 'file2.txt', ...]
with open('path/to/output/file', 'w') as outfile:
    for fname in filenames:
        with open(fname) as infile:
            for line in infile:
                outfile.write(line)

This method iterates through each file, reading and writing lines sequentially. It's efficient for large files.

For Small Files:

filenames = ['file1.txt', 'file2.txt', ...]
with open('path/to/output/file', 'w') as outfile:
    for fname in filenames:
        with open(fname) as infile:
            outfile.write(infile.read())

For smaller files, this approach reads the entire contents of each file at once, reducing the number of file operations.

An Alternative Using itertools:

filenames = ['file1.txt', 'file2.txt', ...]
with open('path/to/output/file', 'w') as outfile:
    for line in itertools.chain.from_iterable(itertools.imap(open, filnames)):
        outfile.write(line)

This method uses the itertools module to iterate over lines across multiple files as if they were a single list. It's less memory-efficient but can be considered an intriguing approach.

By employing these more elegant techniques, you can concatenate text files in Python with greater ease and efficiency, catering to scenarios involving both large and small files.

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