List the percentage change in text between each commit and the previous commit. Can be more than 100.

commit_sizes.py

import subprocess
import sys
import csv
# uses the GitPython module
import git
from pathlib import Path

## Notice need to install GitPython
## Recommended:
## python3 -m venv .venv
## source .venv/bin/activate
## pip3 install GitPython
## To use on the file causal_inference.Rmd at the unix/mac command line:
## python3 commit_sizes.py causal-inference/causal-inference.Rmd

## basically we just need to give it the path to a file
file_path = sys.argv[1]

def get_commits_for_file(file_path):
  try:
    repo = git.Repo(".",search_parent_directories=True)  # Open the Git repository
    commits = list(repo.iter_commits(paths=file_path,reverse=True))  # Efficiently iterate using paths argument

    commit_shas = []
    for commit in commits:
      commit_shas.append(commit.hexsha[:7])  # Capture the first 7 characters of the SHA

    return commit_shas

  except git.exc.NoSuchPathError:
    print(f"Error: File '{file_path}' not found in repository.")
    return []  # Return an empty list on error

#file_path = "causal-inference/causal-inference.Rmd"
#commits = get_commits_for_file(file_path)
##
##if commits:
##  print("Commits for", file_path, ":")
##  for commit_sha in commits:
##    print(commit_sha)
##else:
##  print("No commits found for", file_path)


def get_commit_diff(commit_hash, file_path):
    result = subprocess.run(
        ['git', 'diff', commit_hash, commit_hash + '^', file_path],
        capture_output=True,
        text=True
    )
    return result.stdout.split('\n')

def count_words(diff_lines):
    added_words = 0
    deleted_words = 0
    for line in diff_lines:
        if line.startswith('+'):
            added_words += len(line[1:].split())
        elif line.startswith('-'):
            deleted_words += len(line[1:].split())
    return added_words, deleted_words

def calculate_percentage_change(added_words, deleted_words, total_words):
    return (added_words + deleted_words) / total_words * 100

def main():
    #file_path = 'causal-inference/causal-inference.Rmd'
    repo = git.Repo(".",search_parent_directories=True)  # Open the Git repository
    commits = get_commits_for_file(file_path)

    with open('output.csv', 'w', newline='') as csvfile:
        fieldnames = ['commit', 'percentage_change']
        writer = csv.DictWriter(csvfile, fieldnames=fieldnames)

        writer.writeheader()
        for commit in commits:
            if not commit:
                continue
            if commit == commits[0]:
                percentage_change = 100
            else:
                the_commit_obj = repo.commit(commit)
                git_blob = the_commit_obj.tree / file_path
                file_content = git_blob.data_stream.read().decode('utf-8')
                total_words = len(file_content.split())
                diff_lines = get_commit_diff(commit, file_path)
                added_words, deleted_words = count_words(diff_lines)
                percentage_change = calculate_percentage_change(added_words, deleted_words, total_words) 
            writer.writerow({'commit': commit, 'percentage_change': percentage_change})

if __name__ == '__main__':
    main()