Cheat sheet for development in Python

Snippet

Environemnt Variables

import os

os.getenv("ENV_VAR_NAME", "default_value")

os — Miscellaneous operating system interfaces — Python 3.12.3 documentation

Command Line Argument

import argparse

parser = argparse.ArgumentParser(description='Parse command line options.')
parser.add_argument('integers', metavar='c', type=int, nargs='+',
                    help='an integer for the accumulator')
parser.add_argument('--sum', dest='accumulate', action='store_const',
                    const=sum, default=max,
                    help='sum the integers (default: find the max)')

args = parser.parse_args(['--sum', '7', '-1', '42'])
print(args.accumulate(args.integers))

argparse — Parser for command-line options, arguments and sub-commands — Python 3.12.3 documentation

Random number

import random
x = random.randint(0, 100) # 0 <= x <= 100

Logging

from logging import basicConfig, getLogger, DEBUG

# put in entry point file
CHAR_GREEN = '\033[32m'
CHAR_RESET = '\033[0m'
FORMAT = f"{CHAR_GREEN}%(asctime)s %(levelname)s %(name)s {CHAR_RESET}: %(message)s"
basicConfig(level=INFO, format=FORMAT)

# put in all files
logger = getLogger(__name__)

# logging code
logger.info('hello')

Ref: ログ出力のための print と import logging はやめてほしい #Python - Qiita

Packages

Code formatter

Install packages

pip install \
  black \
  autopep8 \
  isort \
  ;

Run installed packages

black .
autopep8 --recursive --in-place --aggressive --aggressive .
isort .

Package Manager

Poetry

Setup project

cd <project_root>
poetry init

Add a package

poetry add <package_name>

Install dependencies using poetry

poetry install

venv

Create venv

python -m venv .venv

Activate venv

source .venv/bin/activate

Install package

pip install <package_name>

pyenv

Check installed version list

pyenv versions

Get version list

pyenv install -l

Install specific version

pyenv install <python_version>

Get global version

pyenv global

Get local version

pyenv local