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Radon - Keep your Code Easy to Understand

Writing code can be difficult, writing simple code can be even harder. To ensure you don’t get carried away you can use one of the many tools to assess the “quality” of labour.

radon is a very useful tool for peer reviewing your code. It has three modes performing analysis of your code that we will touch on below.

cc - Compute Cyclomatic Complexity

Cyclomatic complexity is a software metric, used to indicate the complexity of a program. It is a quantitative measure of the number of linearly independent paths through a program’s source code. but for a quick start to the following:

Here we use it to get a rough grading of our python file, A is good, all the way down to E which as you might expect is bad.

$ radon cc my-package
    F 178:0 format_monkey_tree - B
    M 111:4 MonkeyNode.validate - B
    M 153:4 MonkeyNode.__eq__ - B
    F 205:0 build_monkey_tree - B
    M 56:4 MonkeyNode.__init__ - A
    F 240:0 iter_critical_errors - A
    M 75:4 MonkeyNode.new_value - A
    M 95:4 MonkeyNode.has_critical_errors - A
    M 101:4 MonkeyNode.iter_monkeys - A
    M 106:4 MonkeyNode.iter_nodes - A
    M 166:4 MonkeyNode.__ne__ - A
    M 172:4 MonkeyNode.__repr__ - A
    C 31:0 InvalidatingMonkeyError - D
    M 32:4 InvalidatingMonkeyError.__init__ - D
    C 37:0 MissingMonkeyError - A
    M 38:4 MissingMonkeyError.__init__ - A
    C 17:0 MonkeyCalculator - A
    M 31:4 MonkeyCalculator.healthyness - A

The above is the output from a fictional project. The filename is on the right and the rating is the letter after -. It’s not bad overall, mostly As with a few Bs and Ds thrown in.

Low ratings are an indicator of complex which has the potential to cause issues with maintenance and development issues later in the life of the project.

The output gives you a list of priorities for you refactoring.

raw - Raw Statistics

$ radon raw my-package
    LOC: 1
    LLOC: 1
    SLOC: 1
    Comments: 1
    Single comments: 0
    Multi: 0
    Blank: 0
    - Comment Stats
        (C % L): 100%
        (C % S): 100%
        (C + M % L): 100%
    LOC: 529
    LLOC: 175
    SLOC: 348
    Comments: 27
    Single comments: 30
    Multi: 61
    Blank: 90
    - Comment Stats
        (C % L): 5%
        (C % S): 8%
        (C + M % L): 17%

mi - Maintainability Index

$ radon mi my-package
runner/__init__.py - A
my-package/complex_module/service.py - A