Understand Python Packages in Details

Last Updated on February 13, 2023 by Prepbytes

A collection of modules that all have a common purpose is called a python package. Python packages are used to organize all modules with appropriate structures so that users can use them easily. Python Packages can contain sub-packages, modules, and other resources like data files, etc.

What are Python Packages?

A Python package is a module-level organization of code that allows for code reuse, modularity, and abstraction. It is a directory structure that contains Python modules, sub-packages, and other resources like data files, etc.

Example of Python Packages

An example of a Python package is the NumPy package, which stands for Numerical Python. It provides support for arrays and matrices and includes functions for numerical operations, linear algebra, and random number generation. It is commonly used for scientific and engineering applications.

To install the NumPy package in your device enter the below command in the terminal or command line.

pip install numpy

After completion of the installation, use the below statement in your code to use the numpy module.

import numpy as np

Let’s see how we can use the above python package in a python code.

import numpy as np

matrix = np.zeros([3, 3])
print("\nMatrix : \n", matrix)

Output:

Matrix : 
 [[0. 0. 0.]
 [0. 0. 0.]
 [0. 0. 0.]]

How to Create a Python Package?

Following the below simple steps you can create your own python packages.

• Choose a name for your package and create a directory with that name.
• Create an init.py file in the package directory. This file can be empty, but it signals to Python that this directory should be considered a package.
• Create one or more Python modules (i.e., .py files) in the package directory, containing the functions and classes you want to include in your package.
• Define the package’s API in the init.py file. This can include importing modules and sub-packages and defining variables and functions that should be exposed to users of the package.
• Write documentation for your package, describing what it does and how to use it.

Now, let’s see how we can create a python package using the above steps.

We will create a calculator package with modules addition, subtraction, multiplication, and division.

Now, let’s create all these modules.

addition.py

def add(a,b):
    return a+b

subtraction.py

def sub(a,b):
    return a-b

multiplication.py

def mul(a,b):
    return a*b

division.py

def div(a,b):
    return a/b

Below is the folder structure of the python package.

calculator

     |
     |
     |------ __init__.py
     |
     |
     |------ addition.py
     |      |
     |      |---------- add()
     |
     |
     |------ subtraction.py
     |      |
     |      |---------- sub()
     |
     |
     |------ multiplication.py
     |      |
     |      |---------- mul()
     |
     |
     |------ division.py
        |
        |---------- div()

Why to use init.py?

init.py file is used to define the package’s API and can be empty or can contain code that initializes the package. We can also mention specific functions from the module to use in this file. Let’s see how the init.py file look.

init.py

from .addition import add
from .subtraction import sub
from .multiplication import mul
from .division import div

How to Import Modules from the Python Packages.

We can import modules from the python packages using import and from keyword and using . operator. The syntax to import the module from the python packages is given below.

Syntax:

Import package_name.mudule_name

Example: Program to import modules from the package
In this example, we will import the module from the package, and then we will use the functions of that python package.

Code:

from calculator import addition
from calculator import subtraction
from calculator import multiplication
from calculator import division

print("Addition of 8 and 4 is:", addition.add(8, 4))
print("Subtraction of 7 and 2 is:", subtraction.sub(7, 2))
print("Multiplication of 3 and 4 is:", multiplication.mul(3, 4))
print("Division of 12 and 3 is:", division.div(12, 3))

Output:

Addition of 8 and 4 is: 12
Subtraction of 7 and 2 is: 5
Multiplication of 3 and 4 is: 12
Division of 12 and 3 is: 4.0

Example: Program to import specific function from the module
In this example, we will directly import the specific function from the module of the python package.

Code:

from calculator.addition import add
from calculator.subtraction import sub
from calculator.multiplication import mul
from calculator.division import div

print("Addition of 5 and 4 is:", add(5, 4))
print("Subtraction of 10 and 2 is:", sub(10, 2))
print("Multiplication of 3 and 4 is:", mul(3, 4))
print("Division of 12 and 3 is:", div(12, 3))

Output:

Addition of 5 and 4 is: 9
Subtraction of 10 and 2 is: 8
Multiplication of 3 and 4 is: 12
Division of 12 and 3 is: 4.0

Conclusion
In conclusion, this article will help you to understand what python packages are and this article will also help you to learn how to use python packages. In addition, you will also learn how to create your own python packages.

FAQs Related to Python Packages

1. What is the difference between a python module and a python package?
A module is a single file that contains Python code and can be imported into other Python files. A package is a collection of modules organized into a directory structure. Packages provide a way to distribute and reuse code and organize modules into a logical structure.

2. How do I install a Python package?
The pip package manager can be used to install python packages. To install a package, run the following command in the command line or terminal:
pip install package_name

3. How do I know if a package is compatible with my version of Python?
The compatibility of a package with your version of Python is usually listed in the package’s documentation or on its PyPI page. You can also check the dependencies of the package to see if they are compatible with your version of Python.

4. Can I use Python packages in other programming languages?
Yes, you can use Python packages in other programming languages. For example, you can use the ctypes library in Python to call functions in a shared library, or you can use the swig tool to generate bindings for other programming languages.

5. What is a virtual environment in Python?
A virtual environment in Python is a separate environment that allows you to install packages and run Python scripts without affecting the global environment. Virtual environments are useful for managing dependencies and isolating different projects from each other.