Radon is a Python tool that computes various metrics from the source code. Radon can compute:

• McCabe's complexity, i.e. cyclomatic complexity
• raw metrics (these include SLOC, comment lines, blank lines, &c.)
• Halstead metrics (all of them)
• Maintainability Index (the one used in Visual Studio)

Radon will run from Python 2.6 to Python 3.3 with a single code base and without the need of tools like 2to3 or six. It can also run on PyPy without any problems (currently only PyPy 2.0.0 is tested).

Radon does not depend on any other Python package (except Baker for the command line, but it is an optional dependency).

With Pip:

$ pip install radon

Or download the source and run the setup file:

$ python setup.py install

Radon can be used either from the command line or programmatically. Documentation is at https://radon.readthedocs.org/.

Quick example:

$ radon cc -anc ../baker/baker.py
../baker/baker.py
    M 581:4 Baker.parse_args - D
    M 723:4 Baker.parse - D
    M 223:4 Baker.command - C
    M 796:4 Baker.apply - C
    M 857:4 Baker.run - C

32 blocks (classes, functions, methods) analyzed.
Average complexity: B (6.15625)

Explanation:

• cc is the radon command
• -a tells radon to calculate the average complexity at the end
• -nc tells radon to print only results with a complexity rank of C or worse. Other examples: -na (from A to F), or -nd (from D to F).

Actually it's even better: it's got colors!

If you are looking to use radon on a CI server you may be better off with xenon. Although still experimental, it will fail (that means exiting with a non-zero exit code) when various thresholds are surpassed. radon is more of a reporting tool, while xenon is a monitoring one.

• Documentation: https://radon.readthedocs.org
• PyPI: http://pypi.python.org/pypi/radon
• Issue Tracker: https://github.com/rubik/radon/issues