Fill Versions From Python Environment

Script that fills in versions into your requirements file

Would you like to have all versions set into your requirements.txt? Perhaps you don’t want the full version pinning of all dependencies, but just would like the top package versions locked? All the PyPi package versions are already in your virtual environment, and you don’t want to have to fill them in manually?

Use the Python script below to write your fancy new file into requirements_new.txt for review. All your comments will be preserved. If you have any issues or suggestions, let me know. Enjoy, its Apache 2 licenced.


A script that reads pip freeze, and fills in missing versions into requirements.txt for corresponding packages.
If the version in requirements.txt does not match print a warning. Ignore comments in requirement.txt.

import re
import subprocess

# Get the output of pip freeze
pip_freeze =["pip", "freeze"], capture_output=True, text=True)
pip_freeze_output = pip_freeze.stdout

# Read the contents of requirements.txt
with open("requirements.txt", "r") as f:
    requirements_txt =

# Split the output of pip freeze into individual packages
pip_freeze_lines = pip_freeze_output.split("\n")
pip_freeze_packages = {}
for line in pip_freeze_lines:
    # Ignore empty lines
    if line == "":

    # Split the line into package name and version
    package, version = line.split("==")
    pip_freeze_packages[package] = version

# Split the contents of requirements.txt into individual packages
requirements_txt_lines = requirements_txt.split("\n")
requirements_txt_packages = {}
requirements_txt_lines_result = []
for line in requirements_txt_lines:
    # Ignore empty lines
    if line.strip() == "" or line.strip().startswith("#"):

    elif '==' not in line:
        requirements_txt_packages[line] = None
        version = pip_freeze_packages.get(line)
        if version is None:
            print(f'WARNING: Requirement {line} not installed!')

            requirements_txt_lines_result.append(line + '==' + version)

        # Split the line into package name and version
        package, version = line.split("==")
        freeze_version = pip_freeze_packages.get(package)
        if version != freeze_version:
            print(f'WARNING: Requirement {line} does not match installed version: {freeze_version}')

        requirements_txt_packages[package] = version

# Update the versions in requirements.txt
with open("requirements_new.txt", "w") as f:
    for line in requirements_txt_lines_result:

Created on 24 Jan 2023. Updated on: 24 Jan 2023.
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