Starting a package

Developing Python Packages

James Fulton

Climate informatics researcher

Why build a package anyway?

To make your code easier to reuse
To avoid lots of copying and pasting
To keep your functions up to date
To give your code to others

Course content

You will build a full package, and cover:

File layout
Import structure
Making your package installable
Adding licenses and READMEs
Style and unit tests for a high quality package
Registering and publishing your package to PyPI
Using package templates

Scripts, modules, and packages

Script - A Python file which is run like python myscript.py
Package - A directory full of Python code to be imported
- e.g. numpy
Subpackage - A smaller package inside a package
- e.g. numpy.random and numpy.linalg
Module - A Python file inside a package which stores the package code.
- e.g. example coming in next 2 slide
Library - Either a package, or a collection of packages
- e.g., the Python standard library (math, os, datetime,...)

Directory tree of a package

Directory tree for simple package

mysimplepackage/
|-- simplemodule.py
|-- __init__.py

This directory, called mysimplepackage, is a Python Package
simplemodule.py contains all the package code
__init__.py marks this directory as a Python package

Contents of simple package

__init__.py

Empty file

simplemodule.py

def cool_function():
    ...
    return cool_result

...

def another_cool_function():
    ...
    return another_cool_result

File with generalized functions and code.

Subpackages

Directory tree for package with subpackages

mysklearn/
|-- __init__.py
|-- preprocessing
|   |-- __init__.py
|   |-- normalize.py
|   |-- standardize.py
|-- regression
|   |-- __init__.py
|   |-- regression.py
|-- utils.py

Let's practice!

Developing Python Packages