Can I use GitPython to diff two individual files that are not in a Git repo?

[roadfar]

Can I use GitPython to diff two individual files that are not in a Git repo? Using the Diff class?

[Byron]

No, but I am sure there are python packages that will do so.

What follows is LLM generated, and seems plausible, but is untested.

How to create a diff of two files in python? The usage of external packages is acceptable.

To create a difference (diff) between two files in Python, you can use the difflib module which is part of the standard library. However, if you're open to using external packages, unidiff is a powerful tool for parsing and generating unified diffs.

Here's how you can do it using both methods:

Using difflib

The difflib module provides classes and functions for comparing sequences, including files. Here’s an example of how to generate a diff between two text files:

import difflib

def compare_files(file1, file2):
    with open(file1, 'r') as f1:
        lines1 = f1.readlines()
    with open(file2, 'r') as f2:
        lines2 = f2.readlines()

    diff = difflib.unified_diff(lines1, lines2, fromfile=file1, tofile=file2)
    return '\n'.join(diff)

if __name__ == "__main__":
    file1 = 'path/to/file1.txt'
    file2 = 'path/to/file2.txt'
    print(compare_files(file1, file2))

Using unidiff

If you need more advanced features or better performance, consider using the unidiff package. You can install it via pip:

pip install unidiff

Here’s an example of how to use unidiff to generate a diff:

from unidiff import PatchedFile

def create_diff(file1, file2):
    with open(file1, 'r') as f1:
        lines1 = f1.readlines()
    with open(file2, 'r') as f2:
        lines2 = f2.readlines()

    diff = difflib.unified_diff(lines1, lines2, fromfile=file1, tofile=file2)
    patch = PatchedFile.from_string('\n'.join(diff))
    return str(patch)

if __name__ == "__main__":
    file1 = 'path/to/file1.txt'
    file2 = 'path/to/file2.txt'
    print(create_diff(file1, file2))

In this example, we first generate the diff using difflib, then parse it with unidiff to get additional functionality if needed.

Explanation

• difflib: This is straightforward and doesn't require any external dependencies since it's part of Python's standard library. It generates a unified diff, which is a human-readable format showing the differences between two sequences.

• unidiff: This package provides more features for working with diffs, such as parsing and manipulating patch files. It's useful if you need to perform operations beyond just generating a diff, like applying patches or analyzing changes in detail.

Choose the method that best fits your needs based on whether you want simplicity (using difflib) or additional functionality (using unidiff).

[roadfar]

@Byron Thanks a lot! I want to use the four Git diff algorithms (Myers, Minimal, Histogram, and Patience) in Python code, but it seems that no Python module has such APIs.

[AlexandrDragunkin]

Here is a working option

import difflib
from unidiff import PatchedFile, PatchSet

def create_diff(file1, file2):
    with open(file1, 'r',encoding='utf-8') as f1:
        lines1 = f1.readlines()
    with open(file2, 'r',encoding='utf-8') as f2:
        lines2 = f2.readlines()

    diff = difflib.unified_diff(lines1, lines2, fromfile=file1, tofile=file2)
    diff_string = ''.join(diff)  
    # patch = PatchedFile.from_string(diff_string)
    patch = PatchSet.from_string(diff_string)
    return str(patch)

if __name__ == "__main__":
    file1 = r"path/to/file1.txt"
    file2 = r"path/to/file2.txt"
    print(create_diff(file1, file2))
    

result

--- c:\REPO\path\to\file1.txt
+++ c:\REPO\path\to\file2.tx
@@ -6021,28 +6021,6 @@
         k3.setucs(k3.k_delete, cursnm)
         if exp_p.result_hh:
             k3.visible(exp_p.parent)
-
-    #-------------------------------------------------------------------------------
-    # cursnm = get_random_name(pref="u")