Tips to write pythonic

February 2, 2020

2 minutes read

Python community has a special words for talking about code that follows the best practices for writing in python, pythonic. The following are some tips to make the most of Python programming language.

I recommend as reference the PEP-8¹ (Python Enhancement Proposal) document which provides guidelines and best practices on how to write Python code. It enables to achieve better readability and consistency throughout code.

Naming

Never use l, 0 or I for variable names, as these can be mistaken for 1 and 0. O = 2 is weird
Choose explicit names. learning_rate is better than lr

Topic	Good examples	Bad examples
Function	function, my_function	MyFunction, func
Variable	x, var, my_variable	Var, Myvar
Class	Model, MyClass	model, my_class
Method	class_method, method
Constant	CONSTANT, MY_CONSTANT	myconstant
Module	module.py, my_module.py	my-module.py
Package	package, mypackage

Blank lines

Blank lines help readability

class MIDIScore:
    def my_method(self):
        pass
 
    def my_other_method(self):
        pass


class Pianoroll:
    pass

Line breaking

Use maximum line length of 79

Break lines if necessary, with ( ), \

total = (first_variable
        + second_variable
        - third_variable)

from mypkg import example1, \
                  example2, example3

Indentation

Use it to improve readability

def train(model, weights, data,
          epochs, batch_size):
    model.load_weights(weights)
    model.fit(data, epochs, batch_size)

Use built-in libraries

Instead of reinventing the wheel, most common processing can be done using built-in features of python default libraries.

Handling command-line arguments

argparse

Logging info, error or warning messages

logging

Using paths

pathlib

  from pathlib import Path
  # Define Path object
  data_path = Path("/data/")
  # Composing paths
  mozart_k330_path = data_path / "midi" / "mozart_k330.mid"
  # Iterating over list of .mid files, following subdirectories
  for p in (data_path / "midi").glob("**/*.mid"):
print(p)
  # Open file
  with mozart_k330_path.open('r') as f:
pass

Implementations

Use startwith and endwith methods for str objects

# Not recommended :(
if word[:3] == 'cat':
    print('The word starts with "cat"')

# Recommended :)
if word.startswith('cat'):
    print('The word starts with "cat"')

Use pathlib

from pathlib import Path
data_path = Path("/home/adam/")
midi_path = data_path / "midi"
# Be careful of errors, sometimes use str(midi_)

Footnotes

PEP 8 – Style Guide for Python code https://www.python.org/dev/peps/pep-0008/

Adam Oudad