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Python Packages

Video link: https://youtu.be/TIt2EOuC-Bo

In this video, we learned about Python packages with the help of examples. We also learned about pip, the standard package manager of Python.

Programs in the Video

Python Packages

A package is a directory containing multiple modules and other sub-packages.

Suppose we are developing a game with multiple objects, so it may have these different modules.

  • player.py
  • boss.py
  • gun.py
  • knife.py

Since these modules are in the same location, they look cluttered. We can structure them in this way:

  • game
    • characters
      • player.py
      • boss.py
    • weapons
      • gun.py
      • knife.py

Here, the similar player and boss modules are kept under the characters package. Also, gun and knife modules are kept inside the weapons package.

Then, both characters and weapons packages are kept inside the main game package.

As you can see, our project looks much more organized and structured with the use of packages.

Let's implement this in code.

  1. Create a directory named game that will contain all our game components.
  2. We also need to create an __init__.py file inside game directory. This special file tells Python that this directory is a Python package.
  3. Also create the characters package with an __init__.py file.
  4. Now, create player.py and boss.py modules inside characters package.

In player.py:

def get_player_info():
    print("I am the main player.")

In boss.py:

def get_boss_info():
    print("I am the enemy player.")

While developing large programs, these modules might contain classes and multiple functions.

Let's create a main.py file outside game package.

I can now import and use them in the following ways:

import game.characters.player
game.character.player.get_player_info()

Output

I am the main player.

from game.characters import player
player.get_player_info()

Output

I am the main player.

from game.characters.boss import get_boss_info
get_boss_info()

Output

I am the enemy player.

Note: When you use packages, always try to give descriptive names to functions and classes so that you don't get confused.

Using __init__.py

The code inside __init__.py runs automatically when we import the package.

Let's add a print statement in this file inside the game package.

print("Initializing game features")

When we run this code:

from game.characters import player
from game.characters.boss import get_boss_info

player.get_player_info()

get_boss_info()

We get:

Output

Initializing game features
I am the main player.
I am the enemy player.

Python pip

There are thousands of useful packages tailored for specific tasks that are developed and maintained by the active Python community.

When you start working on more advanced projects, you will have to use these packages at some point rather than building everything from scratch.

For example, if you are working with web development, you will probably use packages like django or flask.

pip is the standard package manager for Python which helps to install and manage additional packages that are not available in the Python standard library.

Installing packages

pip install <package_name>

For example, to install the pandas package, a popular package for data analysis in Python.

pip install pandas

Installing Specific version of a package

To install version 2.21.0 of requests package,

pip install requests==2.21.0

List all packages with pip

pip list

Remove Packages with pip

pip uninstall numpy

This uninstalls the numpy package from our machine.