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 3.4 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 depends on as few packages as possible. Currently only mando is strictly required (for the CLI interface). colorama is also listed as a dependency but if Radon cannot import it, the output simply will not be colored.

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 sympy/solvers/solvers.py -a -nc
sympy/solvers/solvers.py
    F 346:0 solve - F
    F 1093:0 _solve - F
    F 1434:0 _solve_system - F
    F 2647:0 unrad - F
    F 110:0 checksol - F
    F 2238:0 _tsolve - F
    F 2482:0 _invert - F
    F 1862:0 solve_linear_system - E
    F 1781:0 minsolve_linear_system - D
    F 1636:0 solve_linear - D
    F 2382:0 nsolve - C

11 blocks (classes, functions, methods) analyzed.
Average complexity: F (61.0)

Explanation:

• cc is the radon command to compute Cyclomatic Complexity
• -a tells radon to calculate the average complexity at the end. Note that the average is computed among the shown blocks. If you want the total average, among all the blocks, regardless of what is being shown, you should use --total-average.
• -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).
• The letter in front of the line numbers represents the type of the block (F means function, M method and C class).

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