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Top 10 products developed using Django

Django is an open-source web development framework. It was developed in 2003 by Adrian Holovaty and Simon Willison when they were working at the Lawrence Journal-World newspaper. Since then Django has been used in the IT industry by large companies to develop highly scalable, reliable, versatile, and secure web applications. Moreover, In the last decade with python gaining its popularity in different sectors ranging from web development to social networking sites, and scientific computation applications, Django is in-demand.

In this blog, We will have a look at top 10 products developed using Django. But, before that lets first check out questions like: Why should one choose Django? What are its features? What makes it different from other frameworks available in the market?

What is Django?
Django is a web development framework based on the Python programming language. It follows the MVT(Model-View-Template) architectural pattern which is one of its key features.

Django offers many different features some of them are

  • Scalability : Django is exceedingly scalable and implies that it can swiftly switch from modest to large-scale projects.
  • Security : Django takes security as its priority and allows users to use in-built classes and middleware to reassure security of applications.
  • Versatility: Django is an extremely versatile framework that can be used to build anything from simple apps with no database to complicated projects with large databases.
  • Rapid development: Django is fully loaded with inbuilt functionalities like administration site, authentication system and many more which allows rapid development of web applications.

Learn more about Django features here.

 

How can Django prove to be a better choice for your project?

  • It is based on the Python programming language which is very easy to learn compared to any other programming language.
  • Its documentation is well-organized and simple to understand
  • It has a huge community support.
  • It can be used to design web applications that are SEO friendly.
  • To make the application more flexible, it includes an inbuilt authentication and administration system.
  • It enables the construction of complex projects at a rapid pace.

Now, We’ll look at the key advantages of using Django by looking at the following products made using this framework.

 

    1. Bitbucket1. Bitbucket
      Bitbucket was launched in 2008 by Jesper Nøhr. Later, It was acquired by atlassian. It is a cloud-based git source code repository hosting service specially developed for professional web developer teams to manage git project repositories during the software development cycle.It is developed using Django, a python-based web development framework. The reasons Django is used by Bitbuket are firstly its vast community support, secondly its in-built functionalities, libraries and modules offered for rapid development of projects.Bitbucket is used to manage git repositories of our projects and its main features include:

      • Pull requests and code reviews
      • Branch comparison and commit history
      • Unlimited private repositories for free (for up to five users)

 

    1. Disqus2. Disqus
      Disqus is one of the major projects developed using Django. It was launched on October 30, 2007 and was developed by Daniel Ha and Jason Yan. Later, it was acquired by Zeta Global on December 5, 2017. It enables you to add commenting and discussion features to your website, as well as monitor user activity and customize ad serving.Django, a python-based web development framework, was used to build Disqus. Djnago was chosen for its magnificent features like exceedingly scalability, rapid development using inbuilt functionalities .Disqus offers features like

      • Easy-to-use plug-in for comments.
      • Advanced analytics tool and configurable ad serving.
      • Easy to integrate

 

    1. 3. Dropbox
      Dropbox is a famous cloud based storage application. Dropbox is founded by Drew Houston and was launched in 2008. It allows you to store files such as documents, video graphics and many more. The files are accessible anywhere at any time when the device is able to access the internet.Dropbox is developed using the Django framework based on python programming language which makes its development so fast. Dropbox is currently using Python 3.5 version.Django is used to develop both the backend server and client side of this application. Different types of files can be stored synchronized and shared using functionalities of Django.Dropbox offers features like

      • Cloud Storage
      • File sharing
      • Productivity tolls
      • Content Collaboration

 

    1. eventbrite4. Eventbrite
      Eventbrite is an event management platform which works as a ticketing service. It was founded in 2006 by Kevin Hartz and Julia Hartz and Renaud Visage. Users can use the service to search for, create, and promote local events.It is developed using Python and some inhouse frameworks but later it switched to Django to make the application more scalable and interactive.Now, it can be scaled to manage the huge number of users and can be constantly given new updates using Django functionalities.Eventbrite offers features like

      • Automated Reminders
      • Online payments
      • Surveys and audience polls
      • Bar-code scanning

 

    1. instagram5. Instagram
      Instagram, one of the most well-known and rapidly-growing social media platforms. It was founded by Kevin Systrom and Mike Krieger. In April 2012, Facebook (now known as meta) acquired it. Instagram is used to form a network with people all over world and share photos and videos with them and like,share or comment on the items shared.It is another website developed with Python and the Django web development framework.
      Instagram deals with a lot of data and user activities. The Instagram team handles all of this with Django, as well as take use of in-built tools that allow them to focus on UI and UX without having to worry about the technology that makes them function.Instagram offers feature like

      • Live video streaming, IGTV, Story sharing
      • Push Notifications for Your Favorite Accounts
      • Photo and Video Filters using machine learning techniques
      • Hyperlink Username and Hashtags

 

    1. mozilla6. Mozilla
      Mozilla, one of the most popular browsers, can handle hundreds of millions of inquiries per month. It was founded in 1998 by members of Netscape later Mozilla 1.0, the first major version, was released in 2002. The Firefox web browser, Thunderbird e-mail client and others are among Mozilla’s current products.Mozilla was originally built with PHP using Cake PHP web development framework but to make the application scalable and versatile they switched to Python using Django framework. Django now powers the Mozilla support website as well as all of their browser add-ons.Features given below are offered by Mozilla Firefox are

      • Page Actions menu: Bookmark, snap, save or share
      • Private Browsing with Enhanced Tracking Protection: Browse fast and free
      • Keep your Firefox in sync
      • Customize the menu or the toolbar

 

    1. 7. Pinterest
      Pinterest is an image-sharing and social media service that uses pin-boards to allow users to save and find content on the internet using photos, animated GIFs and video.
      Ben Silbermann, Paul Sciarra, and Evan Sharp established the site, which had over 430 million global monthly active users as of February 2022. Now, Pinterest, Inc., based in San Francisco, runs the site. Pinterest users can subscribe to other users and share their boards using this framework.Django is a popular choice among social networking networks because it can manage large amounts of data and thousands of user interactions every second.
      Pinterest needs to provide exceptional performance and the capacity to scale effectively while maintaining performance with 250 million monthly active users.Pinterest offers features like :

      • Creative sharing of content or blog
      • Free to use
      • Send pins to friends

 

    1. 8. Spotify
      Spotify is a large database that allows users to listen to music on any device. It was founded on 23 April 2006 by Daniel Ek and Martin Lorentzon. Spotify, like iTunes, revolutionized the way consumers listen to, share, and buy music. You may access your music library from anywhere and on any device when you use it.
      Spotify employs a mix of Java, Python, and C++ and Django to make a backend that is fast and allows options for machine learning to present consumers with personalized auto-generated playlists.Spotify offers features like

      • Find music with Spotify’s recommendations
      • Ability to download songs, albums, and podcasts for offline listening
      • Pin content in your library for easy access

 

    1. thewashingtonpost09. The Washington Post
      The online app for The Washington Post, one of the world’s most influential newspapers, is one of the best Django application examples of this type. The Django framework is used by the Washington Post to handle high loads and provide quick and efficient website performance.The Washington Post, The Guardian, The New York Times, and other newspaper websites that use Django are now highly scalable and capable of handling massive volumes of data supplied by their daily audiences.The Washington Post website, which is entirely developed in Django, received 172 million monthly visits in March 2019.

 

  1. Youtube10. YouTube
    YouTube is a free video-sharing website that makes watching online videos simple.
    You can even make your own videos and post them to enjoy with others.
    YouTube, which was founded in 2005, is currently one of the most popular websites on the Internet, with over 6 billion hours of video watched each month.It was originally designed in PHP, but due to rapid audience growth and the need to quickly incorporate new features, the team decided to join the Django community.
    And the decision was well-founded, as audience growth hasn’t slowed, and new features come on a regular basis.YouTube offers features like

    • Channel dashboard and Analytics
    • Likes, Comment Share and Save video
    • Search engine optimization tools

 

Final Thought
We’ve only shown a few examples of popular Django-powered apps.
There are a lot more Django apps available. Django is an excellent choice for both small and large businesses that want to offer products as rapidly as possible and at a low cost..
You may use this framework to not only build a website, but also to enhance it with new features and updates, as well as scale it for a wider audience.

 

Startxlabs, one of India’s top digital transformation service providers. Launched in 2014, Startxlabs aims in innovating a digital future by developing technology for the web and mobile platforms. From our beginning as a technology development company, we’ve tried to stay true to our core beliefs and to deliver exceptional services to our clients. Whether it’s people we work for or people who work for us, we value honesty, passion, and the desire to explore. We have expertise in website development, android app development, iOS app development, Flutter, React Native app development, UI/UX design, and marketing strategy. With the engagement of our highly technical team, we have delivered over 110+ projects providing a positive impact on the users.

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Why to use PostgreSQL with Django?

We are living in an era where data is considered as the new currency. The more data you have the more rich you are. And, the amount of data available is increasing day by day.To store data available databases are used. Many different types of databases are available now. In this blog, we will learn about one such database PostgreSQL and why it is best choice to use with Django while developing a web application.

Contents

1. Django – Introduction, Features, and Architecture

2. Why do we need a database?

3. PostgreSQL – Introduction, Features and Companies using it

4. PostgreSQL with Django

5. Final thought

What is Django?

Django is an open-source web development framework used to build web applications for different business problems. It is based on the Python programming language. It follows the DRY (Don’t Repeat Yourself) principle to avoid the repetition of unwanted code which the development process to maintain the optimization of code. Django comprises different components like authentication system, Content Management System, database interactions and many more.

It offers features like

  • Rapid development
  • Security
  • Scalability
  • Versatility
  • ORM ( Object Relational Mapper)

Learn more about Django features here.

One of the most important features amongst these is object relational mapper. The ORM helps developers to map data between the models and the database tables without writing any SQL queries. This allows developers to build applications quickly eliminating the time wasted in writing complex queries by using Django inbuilt functions according to their requirements.

It works on the MVT Model View Template architectural pattern for developing web apps.

  • Model: In Django, each model is a class that represents a table in the database and every attribute in the class represents a field in the corresponding table. Models are denied in the models.py file.
  • View: In Django, the view is a function that works as the controller and takes a web request and sends the web responses like HTML pages, XML documents, images, a 404 page not found error, etc.
  • Template: In Django, the Template folder contains all the client-side files like HTML, CSS, and javascript files and keeps the code clean by keeping the backend and frontend code separately.

This MVT structure help developers to keep the codes separately and enable them to change the frontend part of web application without changing the backend business logics.This is especially beneficial while interacting with database.

 

Why do we need a database?

Nowadays, having a web application for your business is a necessity. Having a database for your web applications makes them more versatile, scalable, and interactive. A database allows you to create, store, read, update and delete data whenever needed. For example, If you have a shopping website you will need to store the products details that you have and the order details etc, If you have a social media website you will need to store all the data of all the users what they post, what they like, their comments and many more items or if you have a simple website that shows your company details you must have a page which has a contact form which people can fill and contact you for that you need a database.

Specifically talking about Django, It offers a default SQLite database when you start building an app but it is meant for small projects and it is not too much scalable which is not something you want. That’s why we tend to use different databases with Django to achieve the ACID principle and maintain the scalability of our web application. The Django web framework supports multiple databases. Examples include MYSQL, MongoDB, PostgresSQL, MariaDB, and SQLite.

The Django official documentation preffer PostgreSQL.The Django supports POstgreSQL 9.5 and higher version It uses django.contrib.postgres module to make database operations.Now lets us learn about PostreSQL.

 

What is PostgreSQL?

It is a powerful open-source relational database. With the support of more than 20 years of community development, it is a highly stable database management system with high levels of reliability, integrity, and correctness. A lot of web applications, mobile applications, geo-spatial applications, and analytics applications use PostgreSQL as their primary data store or data warehouse. Currently, PostgreSQL 12 is the latest version. It is also known as Postgres.

Scientists from the University of California at Berkeley created PostgreSQL. It was originally known as Ingres. The creators of this application gradually added more features and improved it over time. As a result, the name was changed to Postgres95 and finally to PostgreSQL.

 

Features of PostgreSQL

  • It allows the development of a fault-tolerant environment by administrators to maintain data integrity.
  • It is compatible with all major programming languages and middle ware.
  • It supports a multi-version concurrency control system
  • It supports client-server network architecture
  • It support both relational(SQL) and non-relational(JSON) querying.
  • It is completely ACID(Atomicity, Consistency, Isolation, and Durability.
  • It is compliant with the ANSI SQL standard

Giant tech companies like Apple, IMDB, Instagram, Reddit,Skype, Spotify uses it. International Space Station also utilize it to store the data on the orbit and then replicate that database on the ground. PostgreSQL is widely used in the Financial Industry, Government GIS data, Manufacturing, Web technology and many more domains.

 

Advantages of using PostgreSQL with Django

  • Django supports richest set of features offered by PostgreSQL.
  • Django has django.contrib.postgres to make database operations on PostgreSQL.
  • Django provides a lot of data types that are only supported by PostgreSQL like ArrayField, HStoreField, and PostgreSQL-specific aggregation which can be used for both general-purpose data aggregation and statistical analytics. The JSONField stores JSON encoded data.
  • As a result of PostgreSQL specific database constraints, developers can specify what kind of data can be inserted into the database. This increases the accuracy and reliability of data in the database.
  • Using the “django.contrib.postgres.forms” module, the Django framework provides form fields and widgets that are specific to PostgreSQL.
  • You must utilize PostgreSQL if you are creating a map-based application or storing geographical data, as GeoDjango is only completely compatible with PostgreSQL.
  • Database functions such as TranscationNow, which return the date and time when the current transaction started on the database server, are specific to PostgreSQL.
  • PostgreSQL specific lookups extend this functionality beyond what is provided by Django’s built-in lookups. There is an unaccent lookup feature available in PostgreSQL, which enables accent-insensitive lookups. PostgreSQL also supports migration of Django Database extensions to PostgreSQL.
  • Additional validators that are specific to PostgreSQL are provide by the “django.contrib.postgres.validators”.
  •  Full-text search functionality is supported by PostgreSQL database which allows searching natural language documents using Django.
  • In addition, PostgreSQL-specific indexes like BrinIndex, BTreeIndex, GinIndex can help users effectively manage large datasets with advanced indexing functionality.

 

Some special cases when PostgreSQL is the best database choice for Django 

  • To store geographical data: If you are using maps in your application, the best choice would be PostgreSQL, since it is completely compatible with GeoDjango.
  • To provide Procedural language support: Python and many other programming languages an be used as procedural programming languages in PostgreSQL.
  • To use JSON: jsonb were added in Postgres 9.4. So it doesn’t require extra NoSQL DB.
  • Data type changes: You can alter the data type of a column in PostgreSQL without having to rewrite the table. Since Postgre 9.1, changing the data type has been faster.

 

Final Thought

Any company’s data is a valuable asset. How you input, access, and utilize that data can either be a time-consuming expense or a game-changer in terms of your company’s efficiency and cost-cutting. After deciding on a framework for developing your business’s application, the next most daunting challenge is deciding on the finest database for the job. In this blog, we learned why PostgreSQL is the finest database to utilize with Django development to create a solution to your business challenge.

Startxlabs, one of India’s top digital transformation service providers. Launched in 2014, Startxlabs aims in innovating a digital future by developing technology for the web and mobile platforms. From our beginning as a technology development company, we’ve tried to stay true to our core beliefs and to deliver exceptional services to our clients. Whether it’s people we work for or people who work for us, we value honesty, passion, and the desire to explore. We have expertise in website development, android app development, iOS app development, Flutter, React Native app development, UI/UX design, and marketing strategy. With the engagement of our highly technical team, we have delivered over 110+ projects providing a positive impact on the users.

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12 Django features that make it the best platform for building Web applications

What is Django?

The Django web development framework is based on Model View Template (MVT) architecture and written in Python to enable the rapid development of web applications. Once the client’s requirements are gathered, it is very easy to create a scalable, secure, and SEO-friendly web application.

Django is an open-source web framework that is highly in demand in the IT industry worldwide. The question that must be striking your mind now is why, after all, this framework is getting so much attention, what exactly makes it unique and the best for web development, so that it has become so popular lately.

So, Let’s dive in to find the answers to these questions. The following blog will introduce you to the features that make Django a powerful and unique web development framework. After reading it, you can decide if it fits your project needs.

Features of Django

  1. Open Source 

    Django is an open-source web development framework which means that it is freely available over the internet and the users can download and successfully use all its features without paying any cost. Using an open-source framework to build a web application automatically reduces the cost of development. Also, Its source code can be very easily downloaded from the public git repository or by writing this in the terminal.

    git clone https://github.com/django/django.git

    Or it can be installed directly in your project by just writing the given code inside the terminal.

    pip install Django

  2. Outstanding documentation

    One of the most essential characteristics of Django is its comprehensive documentation, which makes learning and mastering the framework a breeze. The documentation is very efficiently created using a modular approach in which the architecture on which Django is based, MVT, is kept in different components such as the Model has a different module and view and template has different modules, as well as many other important aspects of Django such as forms, Admin, Security, and Development process, have different modules, making it easier to navigate to the desired topic. There are also modules such as getting started tutorials for beginners and advanced tutorials for advanced users in the documentation.

    This exceptionally well-organized documentation acts as a resource for developers, allowing them to quickly find answers to their questions. As a result, the amount of time spent searching queries has decreased significantly. In comparison to other open-source frameworks, Django has the best documentation.

  3. Rapid development

    Django’s tagline is “The web framework for perfectionists with deadlines.” which means that it is made to develop projects rapidly. Django has become extremely popular as a result of one of its primary features: rapid development. Django has capabilities that eliminate the need to create server files, files to connect to the server, and writing queries to create read, update, or delete database entries, allowing users to construct web applications at a rapid pace. It helps us construct web apps more quickly by reducing project implementation time.

  4. DRY: Don’t Repeat Yourself

    Django is known for its rapid development, as stated above, but how does it do so? The DRY concept, which underpins Django’s rapid development, stands for “Don’t Repeat Yourself.” Most of the time, developers spend the majority of their time managing the programs they’ve developed or rewriting various parts of the code. However, Django provides us with capabilities that eliminate unwanted repeats, allowing us to keep our code clean and manageable.

    In a broader sense, Django divides the project into three modules: Model, View, and Template, with Model containing the database tables, View containing the data manipulation functions and acting as controllers, and Template containing the frontend parts such as HTML pages. Keeping our code as clean and manageable as possible.

  5. Fully Loaded

    Django is loaded with modules and libraries that make developers’ lives easier by handling most web development tasks, such as the authentication system it provides or the content administration system, which is the website’s administration site that can be built with just a few lines of code and makes the application very handy. It also lets us build our own URLs for our web pages and offers a variety of techniques for creating site maps, RSS feeds, and Atom feeds.

  6. Reassuringly Secure

    Another remarkable characteristic of Django is its high level of security. Big organizations like Instagram and Bitbucket, which require a high level of security to protect user data, rely on Django, which excels in this area. SQL injection, cross-site scripting, cross-site request forgery, and clickjacking are all examples of errors that developers make which it always prevents. It has various classes that allow developers to create an authentication system with a few lines of code and manage user accounts and passwords. It has inbuilt classes like Securitymiddleware that increase the security of WebApp.

     

  7. Exceedingly Scalable

    A web application’s scalability refers to its capacity to function effectively as its size and volume grow to meet the needs of the client. Django is a scalable programming language that is currently used by companies such as Instagram, National Geographic, Spotify, Bitbucket, Eventbrite, Prezi, The Washington Times, and many others. Companies such as Disqus, Instagram, Pinterest, and Mozilla have been using Django for many years with no glitches or errors. Furthermore, data show that Django-powered websites have received up to 50 thousand hits per second, indicating Django’s scalability. Django’s versatile nature implies that he can swiftly switch from modest to large-scale projects.

    The number of active users on platforms like Instagram is enormous, and all of those people are creating terabytes of data on a daily basis, which needs to be handled with precision, and Django’s use demonstrates that it is capable of doing so.

     

  8. Incredibly Versatile

    Django is a web development framework with a lot of flexibility. It may be used to create everything from simple apps with no database to complex applications with large databases. Django is now being used to create a wide range of web applications, including content management systems, social networking sites, and scientific computation applications. Instagram, National Geographic, Spotify, and Bitbucket, for example, are all from different domains, yet they all utilize Django currently.

     

  9. SEO optimized 

    Django’s SEO-optimized nature is another fantastic feature that sets it apart from other web frameworks.

    SEO stands for Search Engine Optimization, and as the name implies, it involves adding features to your projects and optimizing them so that they appear towards the top of search results. As we all know, search engines employ algorithms that don’t always work well with site developers. Because we are developing our website in a human-readable format, they must add it to the server in URL format so that it may be recognized by search engines.

    Django clarifies this notion by keeping the website using URLs rather than IP addresses on the server, making it simple for SEO engineers to add the website to the server while the web developer does not have to translate the URL into numeric code.

     

  10. Vast and Supported Community

    Django is one of the most popular web frameworks. It has a large and friendly community as well as channels for sharing and connecting. Django has been around for 13 years, which means it has been used by millions of people and improved by tens of thousands of programmers. It’s really easy to find a community of developers who are well-versed in Django and have coded with it.

    Django has a large community that responds quickly to bugs and fixes them. Django is constantly improving as an open-source framework with the addition of new libraries. As a result, all of your questions are only a click away.

     

  11. ORM ( Object Relational Mapper)

    SQL (Structured Query Language) is a programming language that allows a web application to create a database and perform CRUD (Create, Read, Update, and Delete) operations on it.

    Well, in Django, we have ORM to do the job; each class in the model represents a database table, and we don’t have to write SQL queries to manipulate the database, making life easier for developers with limited SQL knowledge.

     

  12. Admin Interface and Packages

    Another two important and handy aspects of Django are its admin interface and inbuilt packages.

    Django’s Admin Interface helps the clients to manage their applications without getting their hands dirty with the code. Django Packages supports the development process and makes our work easier. For example, Django-rest-framework helps us to easily build and use REST APIs.

     

    Conclusion

    After reading this blog post, you must have a good idea of the most important features of Django and whether or not they meet your requirements. Django is the best for everyone, whether you’re a developer or a client. We learned about some of Django’s features today, but these aren’t the only ones. “The sky’s the limit,” as they say. Django provides a lot more functionality, making it a good choice for your needs.

    Startxlabs, one of India’s top digital transformation service providers. Launched in 2014, Startxlabs aims in innovating a digital future by developing technology for the web and mobile platforms. From our beginning as a technology development company, we’ve tried to stay true to our core beliefs and to deliver exceptional services to our clients. Whether it’s people we work for or people who work for us, we value honesty, passion, and the desire to explore. We have expertise in website development, android app development, iOS app development, Flutter, React Native app development, UI/UX design, and marketing strategy. With the engagement of our highly technical team, we have delivered over 110+ projects providing a positive impact on the users.

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Python Basics: Functions and Variable Scopes

Python is a general-purpose, high-level programming language that has many applications in web development, data science, software development, and more. It was initially released in the year 1991. Programming in Python involves simple syntax and it works on different platforms such as Windows, Mac, Linux, etc. In this article, we will discuss the Python functions.

Python Functions

A function is a set of related statements written to perform a specific task when it is called. It can take parameters and return a result. It is efficient to use several functions inside a program to perform specific tasks rather than merely writing a large program that performs the entire tasks. Functions are reusable and make the program easy to understand.

Syntax of Python Functions

A simple python function appears like

def func_name(parameters):

/* function statements */

return result

The syntax of a Python function can be defined as follows:

  • The def keyword is used to denote the start of a function header
  • Followed by def, the function name should be written according to the rules of writing identifiers in Python
  • A semicolon should be added at the end of the function header.
  • A function can take one or more parameters as arguments.
  • The statements inside the function should follow the proper indentation as shown above.
  • The docstring (document string) specified inside ” ” ”    ” ” ”  (triple quotes) can be used inside the function to define the purpose of the function. Though optional, it is a good practice to use docstring in your function while writing a program.

For example

def my_name(name):

" " " This function displays my name" " "

print("My name is" +name)

Function call

A function can be called in any part of the program or inside another function, by passing appropriate parameters to it.

>>>my_name('John')

My name is John

If you want to print the docstring of the function, you can print it by using,

>>>print(my_name._doc_)

This function displays my name

Return Statement

The ‘return’ statement is placed at the end of the function that returns either data of a specific type or the evaluated result of an expression. If there is no return statement specified as in the above example function, it returns nothing, or to be more precise, a none object is returned.

def sum(num1, num2):

" " " This function adds two numbers " " "

return num1+num2

print(sum(2,3))

Scope of variables and Lifetime

The availability of a variable whether inside or outside of a function is called its scope. A variable declared inside a function has recognition only inside the function and has no scope outside the function. Such variables are called the local variable. A variable declared on the python program (outside a function) is called a global variable and has a scope on the entire code and also inside the functions. You can also make a local variable global by adding the keyword “global” before the variable name.

Lifetime is the period of a variable that has its existence in memory. Variables declared within the function get destroyed when the function completes its execution. However, the global variables persist as long as the entire program is in execution.

We can see an example for local and global variables

def func1():

a=5 //local variable

return a

b=10 //global variable

c=func1()+b //function call

print("Value=" +c)

Output

15

def func1():

a=5 //local variable

return a

b=10 //global variable

c=func1()+b+a //function call

print("Value=" +c)

If you try executing this function it will show an error message like “name ‘a’ is not defined” as we used the variable outside its scope.

There is also another variable called non-local variables that are used within the nested functions. The non-local variables are declared using the ‘nonlocal’ keyword.

There are two types of functions available in Python. They are:

  • Built-in functions: Functions that are already available in Python. There are 68 built-in functions available in the most recent version of python, Python 3. For example, bin() returns the binary value of a number, ASCII() which returns the Unicode value of a character.
  • User-defined: Functions written by the user.

Types of Function Arguments

The values passed to the function as parameters are called the function arguments. There are two types of arguments. They are

  • Fixed arguments: The number of arguments passed during the function call should be equal to the number of arguments that have been declared to a function during its declaration.

For example,

def func1(num1,num2):

return num1+num2

func1(4) /* throws an error as the number of parameters during the function call is not equal to the number of parameters in the declaration */

  • Variable arguments: There is also another way of declaring variables other than fixed arguments. Variables arguments can be passed using 3 methods. They are:
    • Default arguments by using the ‘=’ operator.
def func1(num1=5,num2):

return num1+num2

func1(4)

func1(4,10)

Output

9

14

The function func1 has two arguments, one with the default value and another without any default value. It is mandatory to pass value to the num2 during every function call but passing a value to num1 is optional as it already has a default value and both the function calls will not throw any error here.

  • Keyword Arguments: Keyword arguments are called with the syntax key=value during the function and the order of the arguments is not important here. You can pass the arguments in any order. They are represented as kwargs in Python.
def func1(num1,num2):

return num1-num2

func1(num1=7,num2=6)

func1(num2=10,num1=17)

Output

1

7

  • Arbitrary Arguments: When we don’t know the exact number of arguments we need to pass to a function during a function declaration, we can assign them during the function call using the ‘*’ keyword.
def students(*stud_names):

print("The students are:")

for name in stud_names

print(name)

students("John","Mary","Harry")

Output

The students are:

John

Mary

Harry

Here we don’t know the number of arguments we are going to pass during the function call, so we use a for loop for retrieval of the values of arguments.

Python Recursive Functions

A recursive function is a function which calls itself during execution.

for example,

def factorial(num):
  if num == 1:
    return 1
  else:
    return (num * factorial(num-1))

number = 5
print("The factorial of", number, "is", factorial(number))

Sometimes it is hard to write a function only using iterations. There we can use recursive functions which are comparatively easier than iterative functions. However, sometimes for complex operations, recursive logic may be hard to understand.

Anonymous Function (Lambda Functions)

So far we have seen functions declared with a name followed by the def keyword. It is also possible to declare functions without a function name by using the lambda keyword and such functions are called the anonymous functions or the lambda functions. They are also used with some of the python built-in functions such as filter() and map().

The syntax of an anonymous function is

         lambda arguments: expression

Arguments can be of any number, but there should be only one expression

int = lambda a: a + 5

print(int(10))

Output

15

In this article, we’ve learned about the functions in python, how to declare them, how to define them, the variables’ scope, their lifetime, types of arguments, and also the anonymous functions.

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Python Basics: Data types

Python is an object-oriented, interpreted programming language that is simple and easy to use that has significant applications in software development, web development, data science, and so on. The first thing you can learn in a programming language is its data types. In this article, we will explore the various data types of Python language.

Python has data types such as numbers, lists, tuple, string, set, and dictionary. We will discuss them one by one below.

Numbers

The first data type in this language is the number that has integers, float and complex data types defined as “int”, “float”, and “complex” classes. What differs integers from the float is the presence of decimal points in float. For example, 7 is an integer, and 7.0 is a floating variable. A complex data type consists of two parts, a real part, and an imaginary part. For example, x+iy is a complex number where x is the real part and y is the imaginary part. We can use two functions to determine the class to which a number belongs.

  1. type() – return the type of class of a particular variable
  2. isinstance()- checks whether the given variable belongs to a class or not.

For example,

x = 3
print(type(x))
print(type(3.0))

c = 2 + 5j
print(isinstance(c, complex))

Output

<class 'int'>
<class 'float'>
True

The length of an integer data type can be of anything but the float data type has its accuracy up to 15 decimal places and after that it is inaccurate.

The number system such as binary(base 2), octal(base 8), and hexadecimal(base 16) can be represented using a set of prefixes such as

  • Binary – ‘0b’ or ‘0B’
  • Octal – ‘0o’ or ‘0O’
  • Hexadecimal – ‘0x’ or ‘0X’

The process of converting one data type into another is called type conversion. Automatic conversion happens for certain operations. For example, adding an integer and float will automatically result in a float, as it implicitly converts the integer to float.

>>> 1.0 + 5
6.0

We can also explicitly convert a variable of one data type into another by calling some built-in python functions such as int(), float(), complex().

>>> int(2.2)
2
>>> int(-7.8)
-7
>>> float(9)
9.0

Decimal

When we want the most accurate calculations like financial calculations, where precision is so important, we can use decimal instead of float. It can be used by importing the decimal module.

For example,

The second print statement involving the use of a decimal module results in a number with more accurate precision.

Fractions

If we want to use fractions where the numerator and denominator both are integers, we can import the fraction module.

For example,

import fractions

print(fractions.Fraction(0.5))
print(fractions.Fraction(5,6))

Output

1/2
5/6

Math and Random

The math() and random() modules in python offer a wide range of calculations in trigonometry, logarithms, statistics, etc.

For example,

import math
import random

print(math.pi)
print(math.factorial(4))
print(random.randrange(1, 8))

Output

3.141592653589793
24
5

Lists

The list is one of the most used data types in python that stores a sequence of elements in it. We will discuss briefly how to create a list, how to access elements from it, indexing, and more.

List creation

A list can be created by,

list_name= [ ]

The elements contained inside the square brackets are called the items of a list. The list can be either empty, contains items of the same type, different types, or even a list that contains its items. That is, a list can be

list_name=[ ]
list_name=[ 1,2,3,4,5]
list_name=[1, apple, 2, red, 5.5]
list_name=[1, 2, [red, green, yellow], 3, 4, 5]

Accessing an element

The elements contained inside a list have an index associated with them. The indices start from 0 and should be integers. A list of size 6 (6 elements) has an index starting from 0 to 5. The elements can be accessed using their respective indices.

For example,

 

color_list = ['g', 'r', 'e', 'e', 'n']
print(color_list[0])
print(color_list [2])

Output

g
e

print(color_list [6]) //This throws an "IndexError" as we have used an index that is beyond the index range of this list

Negative Indexing

In python, lists are indexed with a negative index starting from the last item in the list.

For example,

color_list = ['g', 'r', 'e', 'e', 'n']
print(color_list[-1])
print(color_list[-2])
print(color_list[-3])
print(color_list[-4])
print(color_list[-5])

Output

n
e
e
r
g

List Slicing

A range of elements from a list in python can be accessed by using the “:” operator (slicing operator).

For example,

color_list = ['g', 'r', 'e', 'e', 'n']

print(color_list[2:4])
print(color_list[:-3])
print(color_list[3:])
print(color_list[:])

Output

['e', 'e', 'n']
['g', 'r']
['e', 'n']
['g', 'r', 'e', 'e', 'n']

Addition/ Modification

Lists elements can be added or modified (mutable) by using the ” = ” operator.

For example,

color_list = ['g', 'r', 'e', 'e', 'n']
color_list[0] = b

print(color_list)

color_list[1:4]=['l', 'a', 'c', 'k']

print(color_list)

Output

['b', 'r', 'e', 'e', 'n']
['b', 'l', 'a', 'c', 'k']

We can add elements to the list by using append(),insert() and extend() methods.

For example,

num_list=[1,2,3,4,5]
num_list.append(6) //adds one element at the last
num_list.extend([7,8,9]) //adds a number of elements at the last
print(num_list)

Output

['1', '2', '3', '4', '5', '6', '7', '8', '9']

We can also concatenate two lists by using the ‘+’ operator and multiply to a certain number of times using the ‘*’ operator.

Deletion

Deletion can be performed by using the keywords del, or by using the functions such as remove(), pop(), or clear().

For example

mylist=['1', '2', '3', '4', 5', '6']

del mylist(2) //deletes the element at index 2
del mylist[1:3] //deletes the elements from index1 to 3
del mylist //deletes the entire list

mylist=['a', 'b, 'c', 'd', e', 'f']

mylist.remove('a') //removes the specified element 'a'
mylist.pop //removes the top most(last) element 'f'
mylist.clear() //removes the entire list

Some of the other methods that can be used with the lists are sort(), count(), reverse(), and copy().

Using the “in” keyword, we can check whether an element is present in a list or not and also can be used in list iterations.

Tuples

Tuples are similar to lists in python but they are immutable (cannot be modified).

They can be created by placing the elements inside the () and separated by commas.

For example,

mytuple = (1, 2, 3)

The elements inside the tuples can be of the same data type or different. The tuples can be created with or without a bracket.

Accessing the tuple elements is the same as the list elements. They can be accessed using indexing, negative indexing, and slicing.

For example,

mytuple = (1, 2, 3)

print(mytuple[0]) //1
print(mytuple[-1]) //3
print(mytuple[1:2]) //2,3

Changing the elements in tuples can be done using the concatenation operator and deletion is done by using the keyword del.

Other methods can also be performed using the count(), index(), and a keyword for membership testing and iteration.

The major advantage of using tuples over lists is, iteration in tuples is easier as they are immutable.

Strings

A sequence of Unicode characters that are converted into binary characters for manipulation is called the strings in python. This process of converting a character into a binary number is called encoding and the reverse process is called decoding.

String creation

Strings are the characters that are enclosed within the quotes (either single or double).

For example,

string_name= 'My String'

print(string_name)

Output

My String

Accessing the characters inside a string is the same as accessing the list of tuples. They can be accessed by indexing, negative indexing, or slicing.

For example,

string_name= 'MyString'

print('string= ', string_name)
print('string[0] = ', string_name[0])
print('string[-1] = ', string_name[-1])
print('string[1:5] = ', string_name[1:5])

Output

string= MyString
string[0]= M
string[-1]= g
string[1:5]= yStri

Like tuples, strings are also immutable. We cannot modify or delete a particular character from a string, but we can delete the entire string by using the del keyword.

Some of the other operations performed in strings are concatenate (+),  multiply(*), enumerate(), len(), format(), lower(), upper(), join(), split(), find(),  and replace()

For example,

string_name= 'MyString'

>>>string_name.lower()
'mystring'

>>>string_name.upper()
'MYSTRING'

>>>My String.split()
['My', 'String']

>>>' '.join(['My', 'String'])
'My String'

>>>'My String'.replace('String','NewString')
'My NewString

>>>str1 = 'Hello'
>>>str2 ='How are you?'
>>>print('str1 + str2 = ', str1 + str2)
'Hello How are you?'

>>>print('str1 * 2 =', str1 * 2)
str1*2= HelloHello

Sets

A set is also a mutable data type that consists of unordered unique (immutable) elements in it.

They are used to perform operations like union, intersection, symmetric difference, and more.

Sets can be created by using {} brackets or by calling the set() function which is in-built. Sets can have any number of elements inside it and they can be of either the same or different data types.

For example,

my_set = {1, 2, 3}
print(my_set)

Output

{1, 2, 3}

Empty curly braces may be interpreted as a dictionary in python, so if we want to create an empty, we can do that by using the set() function.

Since sets are unordered, there is no index associated with the elements of sets. So we can add or delete an element from a set by using the functions such as add(), update(), discard() and remove().

For example,

set_name = {1, 3}
print(set_name) //1,3

set_name.add(2)
print(set_name) //1,2,3

set_name.update([2, 3, 4])
print(set_name) //1,2,3,4

set_name.discard(4) //1,2,3

Similarly, we can also use the pop() or clear() method to do the deletion operations.

Sets are used to perform operations like union, intersection, symmetric difference, and more.

For example,

X = {1, 2, 3, 4, 5}
Y = {4, 5, 6, 7, 8}

print(X | Y)
print(X & Y)
print(X ^ Y)

Output

{1,2,3,4,5,4,5,6,7,8}
{4,5}
{1,2,3,4,5,6,7,8}

There are many other built-in functions available to operate with sets. They are all(), any(), enumerate(), len(), max(), min(), sorted(), sum() and more.

There is a function called frozenset() using which can create immutable sets, cannot be changed once assigned.

For example,

X = frozenset([1, 2, 3, 4])

Dictionary

Dictionary is a data type that contains an unordered sequence of items in it and each of its elements is associated with a key/value pair.

A dictionary in python can be created by,

dict_name = {1: 'red', 2: 'green'}

Elements of a dictionary can be accessed by keys associated with them, like the indexes in lists and tuples. Dictionary elements can be accessed using the get() method.

Example:

dict_name = {1: 'red', 2: 'green'}

print(dict_name.get(2))

Output

green

A new addition to a dictionary is done by using the assignment (=) operator. If you are trying to assign a value for an already existing key, the value will get updated. Deletion from a dictionary is done by using methods such as pop(), popitem(), clear(), and del keyword.

There are some built-in functions available to use with the dictionaries. They are  all(), any(), len(), cmp(), sorted().

In this article, we have learned about the different data types such as numbers, lists, tuples, strings, sets, and dictionaries along with their methods of addition, updation, how to access the elements from them, and more.

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