coding-stds-python

Indentation, line-length & code wrapping
    Always use 4 spaces for indentation (don’t use tabs)
    Write in ASCII in Python 2 and UTF-8 in Python 3
    Max line-length: 72 characters (especially in comments)
    Always indent wrapped code for readablility
    
Imports
    Don’t use wildcards
    Try to use absolute imports over relative ones
    When using relative imports, be explicit (with .)
    Don’t import multiple packages per line

Whitespace and newlines
    2 blank lines before top-level function and class definitions
    1 blank line before class method definitions
    Use blank lines in functions sparingly  
    Avoid extraneous whitespace
    Don’t use whitespace to line up assignment operators (=, :)
    Spaces around = for assignment
    No spaces around = for default parameter values
    Spaces around mathematical operators, but group them sensibly
    Multiple statements on the same line are discouraged
    
Comments
    Keep comments up to date - incorrect comments are worse than no comments
    Write in whole sentences
    Try to write in “Strunk & White” English
    Use inline comments sparingly & avoid obvious comments
    Each line of block comments should start with “# “
    Paragraphs in block comments should be separated by a line with a single “#”
    All public functions, classes and methods should have docstrings
    Docstrings should start and end with """
    Docstring one-liners can be all on the same line
    In docstrings, list each argument on a separate line
    Docstrings should have a blank line before the final """
    
Naming conventions
    Class names in CapWords
    Method, function and variables names in lowercase_with_underscores
    Private methods and properties start with __double_underscore
    “Protected” methods and properties start with _single_underscore
    If you need to use a reserved word, add a _ to the end (e.g. class_)
    Always use self for the first argument to instance methods
    Always use cls for the first argument to class methods
    Never declare functions using lambda (f = lambda x: 2*x)