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Understanding Modules and Packages in Python — SitePoint

Understanding Modules and Packages in Python — SitePoint


On this article, we’ll take a look at a number of the ideas concerned when structuring our Python code utilizing modules and packages. We’ll discover ways to create our personal modules, outline features and courses, and the way we are able to use them in different modules or packages. We’ll additionally take a look at create packages, by organizing associated modules in a listing, and import modules from packages. Lastly, we’ll discover a few of Python’s built-in modules and packages.

By the top of this tutorial, we’ll have a stable understanding of construction our code utilizing modules and packages, enormously enhancing our capability to put in writing maintainable, reusable, and readable code.

Desk of Contents
  1. Introducing Modules and Packages
  2. Working with Modules
  3. Introducing Packages
  4. The __all__ attribute
  5. The Python Normal Library and Common Third-party Packages
  6. Packaging and Distribution
  7. Conclusion

Introducing Modules and Packages

A module in Python is a single file that accommodates Python code within the type of features, executable statements, variables, and courses. A module acts as a self-contained unit of code that may be imported and utilized in different packages or modules.

A package deal, alternatively, is a group of modules organized in a listing. Packages permit us to group a number of associated modules collectively below a typical namespace, making it simpler to arrange and construction our code base.

Breaking code down into modules and packages presents immense advantages:

  • Maintainability. Breaking down code into modules helps us make adjustments within the unbiased components of the general utility with out affecting the entire utility, for the reason that modules are designed to solely cope with one a part of the appliance.

  • Reusability. This can be a key a part of software program growth, the place we write code as soon as and we are able to use it in many various components of an utility as many occasions as we would like. This allows us to put in writing clear and dry code.

  • Collaboration. Modular code enhances and permits collaboration. Completely different groups can work on completely different components of the identical utility on the similar time with out interfering with one another’s work.

  • Readability. Breaking down code into modules and packages enhances code readability. We will simply inform what’s occurring in a file. We’d, for instance, have a file named databaseConnection.py: simply from the title we are able to inform that this file offers with database connections.

Working with Modules

Modules could be imported and utilized in different packages, modules, and packages. They’re very helpful in an utility, since they break down the appliance perform into smaller, manageable, and logical items.

As an illustration, say we wish to create an internet utility: the appliance goes to want code for connecting to a database, code for creating database fashions, code that’s going to be executed when a consumer visits a sure route, and so forth.

We will put all of the code in a single file, however then the code in a short time turns into unmaintainable and unreadable. By utilizing modules, we are able to break down the code into items which can be extra manageable. We’ll put all of the code wanted to connect with the database in a single file, code for database fashions is put in one other file, and code for the routes right into a module. Breaking the code down into these modules promotes group, reusability, and maintainability.

Making a easy module

It’s fairly simple to create a module in Python. Say we have now a lot of associated features, variables, and courses: we might put them in a single module, and provides the module any title we would like, but it surely’s advisable to offer our modules descriptive names — simply as with features, variables, courses.

To create a module in Python, open up an IDE or textual content editor, create a file, and provides it a descriptive title and a .py extension. For this instance, let’s name it pattern.py and enter within the following code:

sample_variable  = "This can be a string variable within the pattern.py module"

def say_hello(title):
  return f"Howdy, {title}  welcome to this easy module."

def add(a, b):
  return f"The sum of {a} + {b} is = {a+b}"

print(add(2, 3))

The code above defines a module named pattern.py. It accommodates a variable named sample_variable whose worth is the string "This can be a string variable within the pattern.py module". This module additionally accommodates two perform definitions. When known as, the say_hello() perform takes in a reputation parameter, and it returns a welcome message if we cross a reputation to it. The add() perform returns the sum of two numbers which have been handed to it.

Whereas modules are meant for use in different components of this system or an utility, we are able to run them independently. To run this module, we have to have Python put in in our growth atmosphere. We will run it on the terminal utilizing the next command:

python pattern.py 

Or we are able to use the next command:

python3 pattern.py

It will return the next output:

This can be a string variable in the pattern.py module
Howdy, kabaki welcome to this easy module.
The sum of 2 + 3 is = 5

For one-off module utilization, we are able to run it as a standalone, however most modules are made for use in different modules or different components of a Python program. So to make use of variables, features, and courses from one module in one other module we have now to import the module. There are other ways of importing modules, so let’s take a look at them.

Utilizing the import assertion

We will use the import assertion to make the contents of 1 module accessible to be used in one other module. Contemplate our pattern.py from above: to make use of its contents in one other module, we simply import it:

import pattern

print(pattern.add(2, 3))

The code above exhibits import the features from the pattern.py module, making them accessible to be used within the another_module.py. Observe that, after we import a module, we don’t embody the .py extension; Python robotically is aware of we’re importing a module.

Utilizing the from key phrase

We will additionally use the from key phrase to import particular features or variables. Say a module has a lot of features and variables outlined in it and we don’t wish to use all of them. We will specify the features or variables we wish to use, utilizing the from key phrase:

from pattern import add

print(add(10, 4))

The code above exhibits that we’ve particularly imported the add() perform from the pattern module.

One other advantage of utilizing the from key phrase is that we’ll run the imported perform with out namespacing it or prefixing it with the title of its dad or mum module. As a substitute, we’ll use the perform like we’ve outlined it within the file the place we’re utilizing it. This results in extra concise and readable code.

Utilizing as

We will use as to supply an alias or an alternate title for the module.

At occasions, we might outline module names which can be fairly lengthy or unreadable. Python gives a manner of giving the module imports an alternate or alias, which we are able to use to consult with them within the modules we’re importing them into. To do that, we’ll use the as key phrase:

import pattern as sp

consequence = sp.add(5, 5)

This code exhibits an import of the pattern module, the place the module is being given an alternate title sp. So utilizing sp is simply the identical as calling pattern. Subsequently, utilizing the alias, we have now entry to the variables and features, in the identical manner we might if we have been utilizing the unique title.

Utilizing these three strategies, we’re in a position to make use of the variables or features from one module in one other module, enhancing the readability of our utility the place we don’t have to put the code in a single file.

Whereas naming our modules, it’s good observe to make use of lowercase letters and separate phrases with underscores. As an illustration, if we have now a module for dealing with database connections, we’d title it database_connection.py. To keep away from naming conflicts, attempt to decide on descriptive and distinctive names for modules. If a module title may trigger a reputation conflict with a Python built-in key phrase or module from a third-party library, think about using a unique title or including a prefix that’s related to the mission. Additionally, do not forget that names are case-sensitive in Python, so be certain that to make use of the proper module title when importing.

Total, utilizing modules lets us create and arrange our code in a readable and maintainable manner. And that is very helpful — whether or not we’re engaged on a small script or a big utility. Later, we’ll take a look at some frequent Python normal library modules.

Introducing Packages

A package deal in Python is a manner of organizing associated modules right into a listing. This gives a greater manner of organizing code, enabling us to group modules that serve a typical objective or are a part of the identical element.

Packages are notably helpful when structuring bigger tasks or libraries. As an illustration, contemplate the case of an internet utility the place we have now code for various database fashions, views, and utilities.

It might make a variety of sense if we created a fashions package deal with completely different modules for the completely different fashions in an utility. Say our internet app is a running a blog utility: attainable fashions might be a customers mannequin and a posts mannequin; we’d then create a module for consumer administration, and a module for posts administration, after which put them within the fashions package deal.

It’s necessary to reiterate at this level that modules are particular person information containing Python code: they assist put associated features, courses, and variables inside a single file. In distinction, packages are directories that comprise a number of modules or subpackages. They supply a better degree of group for our code, by grouping associated modules and enabling us to create extra structured and maintainable tasks.

Constructing and managing packages

Whereas packages arrange associated code modules in a single listing, simply placing the modules in a listing doesn’t make it a package deal. For Python to establish a listing as a package deal or a subpackage, the listing should comprise a particular file named __init__.py.

This file notifies Python that the listing containing it must be handled as a package deal or a subpackage. This file might be empty, and more often than not it’s, however it might additionally comprise initialization code, and it performs an important function in Python’s package deal construction and import mechanisms. So utilizing __init__.py tells Python that we’re deliberately making a package deal, thereby serving to it differentiate between a package deal and an unusual listing.

Packages can have a hierarchical construction, that means we are able to create subpackages inside our packages to additional arrange our code. This allows finer and extra managed separation of parts and performance. Contemplate the next instance:

├── __init__.py
├── module1.py
└── subpackage/
  ├── __init__.py
  ├── submodule1.py
  └── submodule2.py

This diagram exhibits my_package is the primary package deal, and subpackage is a subpackage inside it. Each directories have an __init__.py file. Utilizing this type of construction helps us arrange our code right into a significant hierarchy.

Creating packages and subpackages

To create a package deal, we first create a listing that’s going to comprise our modules. Then we create an __init__.py file. Then we create our modules in it, together with any subpackages.

Say we’re constructing a calculator utility: let’s create a package deal for numerous calculations, so create a listing in our terminal or our IDE and title it calculator.

Within the listing, create the __init__.py file, then create some modules. Let’s create three modules, add.py, subtract.py, and multiply.py. Ultimately, we’ll have a listing construction much like this:

├── __init__.py
├── add.py
├── subtract.py
└── multiply.py

Let’s put some samples in these information. Open the add.py module and put within the following code:

def add(a, b):
  Provides two numbers and returns the consequence.

  :param a: First quantity.
  :param b: Second quantity.
  :return: Sum of a and b.
  return a + b

This creates a module for addition, separating it from different calculations. Let’s create another module for subtraction. Open the subtract.py file and put the next code in it:

def subtract(a, b):
  Subtracts two numbers and returns the consequence.

  :param a: First quantity.
  :param b: Second quantity.
  :return: Distinction of a and b.
  return a - b

So in our utility, if we want to benefit from the calculator modules, we’ll simply import the package deal. There are other ways to import from a package deal, so let’s take a look at them within the subsequent part.

Importing from packages

To import modules from packages or subpackages, there are two important methods. We will both use a relative import or an absolute import.

Absolute imports

Absolute imports are used to instantly import modules or subpackages from the top-level package deal, the place we specify the complete path to the module or package deal we wish to import.

Right here’s an instance of importing the add module from the calculator package deal:

from calculator.add import add

consequence = add(5, 9)


The above instance exhibits an exterior module — calculate.py — that imports the add() perform from the add module utilizing an absolute import by specifying absolutely the path to the perform.

Relative imports

Relative imports are used to import modules or packages relative to the present module’s place within the package deal hierarchy. Relative imports are specified utilizing dots (.) to point the extent of relative positioning.

With the intention to show relative imports, let’s create a subpackage within the calculator package deal, name the subpackage multiply, then transfer the multiply.py module into that subpackage, in order that we’ll have an up to date package deal construction like this:

├── __init__.py
├── add.py
├── subtract.py
└── multiply/
  ├── __init__.py
  └── multiply.py

With this setup, we are able to now use relative imports to entry the multiply module from different modules throughout the calculator package deal or its subpackages. As an illustration, if we had a module contained in the calculator package deal that should import the multiply module, we might use the code under:

from .multiply import multiply 

consequence = multiply(5, 9)

Total, relative imports are notably helpful for imports inside a package deal and subpackage construction.

The __all__ attribute

There are occasions after we might use all modules from a package deal or subpackages, or all features and variables from a module, so typing out all names turns into fairly cumbersome. So we would like a technique to specify that we’re importing features and variables {that a} module has to supply or all modules that package deal presents.

To arrange what could be imported when a consumer needs to import all choices from a module or a package deal, Python has the __all__ attribute, which is a particular attribute that’s utilized in modules or packages to manage what will get imported when a consumer makes use of the from module import * assertion. This attribute permits us to specify an inventory of names that might be thought-about “public” and might be imported when the wildcard (*) import is used.

Utilizing the __all__ attribute in modules

In a module, we are able to outline the __all__ attribute to explicitly specify which names must be imported when the from module import * assertion is used. This helps forestall unintended imports of inside names, offering a transparent manner of displaying the features that may be imported publicly and people which can be meant to be used solely within the module.

Right here’s an instance:

__all__ = ['public_function', 'public_variable']

def public_function():
  return "This can be a public perform."

def _internal_function():
  return "That is an inside perform."

public_variable = "This can be a public variable."
_internal_variable = "That is an inside variable."

The code above defines a module named my_module.py, and with the __all__ attribute being set, solely the public_function and the public_variable might be imported when the from my_module import * is used. The perform and variable names beginning with an underscore received’t be imported.

It’s necessary to notice a number of issues. If we all know absolutely the paths to the features beginning with an underscore, we are able to nonetheless import them to our code. Nevertheless, that goes in opposition to the conference of encapsulation, for the reason that underscore (_) denotes them as personal members of the module and signifies that they shouldn’t be used outdoors the module. So it’s good observe to observe Python programming conventions even when Python doesn’t implement strict encapsulation.

Utilizing the __all__ attribute in packages

The __all__ attribute may also be utilized in __init__.py information inside a package deal or subpackage to manage the default conduct of wildcard imports for submodules or subpackages. This may help be certain that solely particular modules are imported when utilizing wildcard imports on packages:

__all__ = ['submodule1', 'subpackage']

from . import submodule1
from . import subpackage

This instance exhibits an __init__.py file specifying that solely submodule1 and subpackage1 might be imported when utilizing from my_package import *. Different submodules or subpackages received’t be imported by default.

As within the case of modules, we are able to nonetheless import the opposite modules not specified within the __all__ attribute checklist if we all know their absolute paths. So the __all__ attribute acts as a conference fairly than as a strict rule. It’s meant to speak what can be utilized publicly from a module or a package deal. It’s, nevertheless, really useful that express imports (import module_name) be used as an alternative of wildcard imports (from module_name import *).

The Python Normal Library and Common Third-party Packages

The Python Normal Library is a group of modules and packages that come included with the Python interpreter set up. These modules present a variety of functionalities — from working with knowledge varieties and performing file operations to dealing with community communication and implementing numerous algorithms.

A few of the generally used modules within the Python normal library embody:

  • os: provides us an API for interacting with the host working system
  • math: gives a variety of mathematical features and constants (helpful when performing numerous mathematical operations in our code)
  • datetime: permits us to work with dates and time in our code
  • json: permits us to deal with JSON knowledge in our code
  • argparse: permits us to create command line interfaces
  • csv: permits us to learn and write CSV information

The usual library accommodates much more modules than these few examples, every with its personal space of utility, implementing the advantages of breaking code down into modules. To be taught extra in regards to the modules on supply, go to the official Python documentation.

The Python Package deal Index and third-party packages

The Python Package deal Index (PyPI) is a repository of third-party Python packages that reach the performance of the Python Normal Library. These packages cowl a variety of domains and supply options to numerous programming challenges. These packages are created by the open-source group. We will additionally create our personal package deal and publish it with the repository.

To handle third-party packages, Python makes use of a software known as pip (Python Package deal Installer). pip permits us to simply set up, improve, and handle packages from PyPI.

We will set up any third-party library utilizing pip:

pip set up package_name

As an illustration, to put in the Django package deal (which is used for internet growth) we are able to run this:

pip set up django

Listed here are examples of some well-liked third-party packages:

  • NumPy: a robust library for numerical computing in Python. It gives help for big, multi-dimensional arrays and matrices, together with a wide range of mathematical features to function on these arrays.

  • Pandas: a library for knowledge manipulation and evaluation. It gives knowledge constructions like DataFrames for effectively dealing with and analyzing tabular knowledge.

  • Matplotlib: a widely-used library for creating static, animated, and interactive visualizations in Python. It presents a MATLAB-like interface for plotting numerous forms of graphs and charts.

  • SciPy: constructed on high of NumPy, SciPy gives further features for optimization, integration, linear algebra, sign processing, and extra.

  • Django: a high-level internet framework for constructing internet functions. It follows the Mannequin-View-Controller (MVC) structure and presents options for dealing with databases, URLs, templates, and extra.

  • Flask: one other internet framework, Flask is extra light-weight and minimal in comparison with Django. It’s supreme for constructing smaller internet functions or APIs.

  • Requests: a package deal for making HTTP requests and dealing with responses. It simplifies working with internet APIs and fetching knowledge from the Web.

The packages listed above are only a few examples of the huge ecosystem of third-party packages accessible on PyPI. Packages like these can save us a variety of effort and time.

Packaging and Distribution

Packaging and distributing our Python tasks permits others to simply set up and use our code. That is particularly necessary after we wish to share our libraries or functions with a wider viewers. Right here’s a quick overview of package deal and distribute our Python tasks.

setuptools for packaging

setuptools is a package deal that gives constructing and packaging capabilities for our Python tasks. It simplifies the method of making distribution packages, together with supply distributions (sdist) and binary distributions (bdist). To make use of setuptools, we sometimes create a setup.py script in our mission’s root listing.

Right here’s a easy instance of a setup.py script:

from setuptools import setup, find_packages

      "console_scripts": [
          "my_script = my_project.my_module:main",

Within the script above, we specify the mission’s title, model, packages, dependencies, and any entry factors utilizing the setup() perform.

twine for publishing

As soon as our mission is correctly packaged utilizing setuptools, we are able to use twine to add our package deal to PyPI for distribution. twine is a software that helps us securely add packages to PyPI.

To make use of twine, we have to set up it:

pip set up twine

We then go to our mission’s root listing and use the next command to add our package deal:

twine add dist/*

Needless to say distributing packages on PyPI requires creating an account and following sure tips. It’s really useful that we learn the official PyPI documentation for detailed directions on packaging and distribution.

A few of the tips:

  • Versioning. Correctly model packages to point adjustments and updates. This helps customers perceive what’s new and ensures compatibility.

  • Documentation. Embrace clear documentation for the code, describing set up and use our package deal. Use instruments like Sphinx to generate documentation.

  • Licensing. Clearly specify the license below which the package deal is distributed to make sure customers perceive how they’ll use it.

  • Testing. Implement testing to make sure the package deal features as anticipated. Instruments like pytest could be useful for writing and operating checks.

By correctly packaging and distributing our Python tasks, we make it simpler for others to entry and use our code, contributing to a extra collaborative and open-source growth atmosphere.


On this tutorial, we’ve explored the ideas of modules and packages in Python and their significance in writing well-organized, maintainable, and reusable code.

Modules are particular person information containing Python code that encapsulate features, courses, and variables. They promote code group inside a single script and facilitate code reuse throughout a number of scripts.

Packages take the idea of modularity to the following degree by permitting us to arrange associated modules into listing hierarchies. This hierarchical construction enhances code group in bigger tasks and fosters a transparent separation of considerations.

As we proceed our Python journey, mastering the artwork of modular programming with modules and packages will undoubtedly contribute to us changing into more adept and environment friendly builders. By leveraging these ideas, we’ll be higher outfitted to sort out complicated tasks and collaborate successfully with different builders.

FAQs About Modules and Packages in Python

What’s a module in Python?

A module in Python is a file containing Python code, features, courses, or variables. Modules permit you to arrange and reuse code by separating it into particular person information.

How do I create and use a module in Python?

To create a module, you merely create a .py file with Python code and reserve it in the identical listing as your Python script. You may then import and use features, courses, or variables from the module utilizing the import assertion.

What’s a package deal in Python?

A package deal in Python is a technique to arrange associated modules into directories and subdirectories. It helps handle and construction bigger Python tasks by grouping associated performance.

How do I create and use a package deal in Python?

To create a package deal, you create a listing and place a number of module information inside it. You additionally embody a particular __init__.py file (which could be empty) to point that the listing is a package deal. You may then import modules from the package deal utilizing dot notation.

How does Python discover and cargo modules and packages?

Python appears for modules and packages in directories listed within the sys.path variable. It searches for them within the present listing and normal library paths. You may also add customized paths to sys.path to make your modules or packages accessible.

What’s a namespace collision, and the way can I keep away from it when utilizing modules and packages?

A namespace collision happens when two modules or packages have the identical title. To keep away from collisions, select distinctive module and package deal names, or use aliasing with the as key phrase when importing to create shorter, distinct names for the imported entities.


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