Day90: Minimal Python package

Like most projects, you start with a question. The how, the why.

While browsing through Twitter for inspiration for today’s post, I stumbled on Ben’s tweet about a new python package he created which does some data science magic.

I am not familiar with what the package does or what it is for, but it got me thinking:

• How does one create a Python package?

I created R packages before, but never Python ones. The repo for this little project is found .

Minimal requirements

According to How to Create a Python Package by Python Central (2012), you need to:

1. Create a directory and give it your package’s name
2. Put your classes (and functions) in it
3. Create a __init__.py file in that directory

Following these instructions, in my “sample-python-package” repository, I (1) created a “mypackage” directory, (2) put my “test1” class inside a script inside that directory, and (3) created a __init__.py file containing the class I want to load at import.

Here is what my file structure look like:

-- sample-python-package
   |-- mypackage
   |   |-- __init__.py
   |   |-- test1.py

Here is the content of “test1.py”:

class Test1:
    def __init__(self):
        ''' Constructor for this class. '''
        self.world = ['Earth', 'Mars']

    def printHello(self):
        for world in self.world:
            print('Hello %s!' % world)

    def printGoodbye(self):
        for world in self.world:
            print('Goodbye %s!' % world)

And here is the content of __init__.py:

# from .<file-name-without-py> import <class>
from .test1 import Test1

Note: It seems leaving __init__.py blank will not load the “Test1” class during import mypackage.

Test case

To test that this minimal package works, on the command line (in the “sample-python-package” directory), I started a ipython session, ran the following commands, and saw the expected outputs which means this is a python package!

import mypackage

t1 = mypackage.Test1()

t1.printHello()
#> Hello Earth!
#> Hello Mars!

Future work

Now that I have a minimal python package working, I want to:

• Enable pip installation
• Enable continuous integration with Travis

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