Extracting Project Dependencies and File Header Comments in Python

To reproduce a Python project's environment, you need a complete list of third‑party packages. For small projects you can manually examine import statements and record direct dependencies. For larger or more complex codebases, automated tools are recommended.

Using pipreqs : Install the tool with pip install pipreqs and run it in the project root: pipreqs /path/to/your/project --force. It scans the source files, detects imported packages, and creates a requirements.txt containing package names and versions.

Using Poetry : If the project already uses Poetry, the dependency tree is stored in pyproject.toml. Export it to a requirements file with poetry export -f requirements.txt > requirements.txt.

Using pipdeptree : Install with pip install pipdeptree. To list all installed packages and their dependencies, run

pipdeptree | awk '/^\w/ {print $1}' | sort -u > requirements.txt

. This produces a flat list of top‑level packages.

Note that some methods may only list direct dependencies; to include transitive (indirect) packages, add the --include-indirect option to pipreqs or configure the chosen tool accordingly.

The second part of the article provides a script for extracting the first line comment from every .py file in a directory and writing the filename‑comment pairs to an output text file.

import os

def get_first_line_comments(directory, output_file):
    # List all .py files except __init__.py and sort them
    python_files = sorted([f for f in os.listdir(directory) if f.endswith('.py') and f != '__init__.py'])
    comments_and_files = []
    for file in python_files:
        filepath = os.path.join(directory, file)
        with open(filepath, 'r', encoding='utf-8') as f:
            # Read the first line
            first_line = f.readline().strip()
            # If the first line is a comment, store it
            if first_line.startswith('#'):
                comment = first_line[1:].strip()
                comments_and_files.append((file, comment))
    # Write the collected filename‑comment pairs to the output file
    with open(output_file, 'w', encoding='utf-8') as out:
        for filename, comment in comments_and_files:
            out.write(f"{filename}: {comment}
")

# Example usage
get_first_line_comments('path/to/your/directory', 'output.txt')