200+ Python Developer Interview Questions and Answers

append adds a single element, while extend adds multiple elements from an iterable to a list.

• append(obj): Adds 'obj' as a single element to the end of the list. Example: lst.append(4) results in [1, 2, 3, 4].

• extend(iterable): Adds each element from 'iterable' to the list. Example: lst.extend([4, 5]) results in [1, 2, 3, 4, 5].

• Use append when you want to add one item; use extend when you want to merge another iterable into the list.

• Both methods modify the original list in plac...read more

Yes, we can create our custom exception in Python.

• To create a custom exception, we need to create a class that inherits from the Exception class.

• We can define our own message and error code for the custom exception.

• We can raise the custom exception using the 'raise' keyword.

• Custom exceptions can be used to handle specific errors in our code.

• Example: class MyException(Exception): pass

• Example: raise MyException('This is a custom exception')

Testers focus on finding defects while developers focus on creating software.

• Testers are responsible for testing the software and finding defects.

• Developers are responsible for creating the software and fixing defects.

• Testers use test cases and scenarios to ensure the software meets requirements.

• Developers use programming languages and tools to create software.

• Testers work closely with developers to ensure defects are fixed.

• Developers work closely with testers to understand a...read more

Python has built-in data structures like lists, tuples, sets, and dictionaries.

• Lists are mutable and ordered, used for storing multiple items.

• Tuples are immutable and ordered, used for storing multiple items.

• Sets are mutable and unordered, used for storing unique values.

• Dictionaries are mutable and unordered, used for storing key-value pairs.

Swap elements in pairs of two in a given list.

• Iterate through the list with a step of 2.

• Swap the current element with the next element.

• Continue until the end of the list or the last pair of elements.

Adding elements to a list, understanding JSON, removing duplicates, and printing prime numbers in Python.

• To add elements to a list in Python, you can use the append() method or the extend() method.

• JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy for humans to read and write, and easy for machines to parse and generate.

• To remove duplicate values from a list, you can convert the list to a set and then back to a list, or use a loop to itera...read more

List and tuple are both sequence data types in Python. Lists are mutable while tuples are immutable.

• Lists are created using square brackets [] while tuples use parentheses ()

• Lists can be modified by adding, removing or changing elements while tuples cannot be modified

• List functions include append(), extend(), insert(), remove(), pop(), index(), count(), sort() and reverse()

• Tuple functions include index() and count()

• Lists are used when the data needs to be modified while tuple...read more

A Python program in recursion

• Recursion is a technique where a function calls itself to solve a problem

• The function should have a base case to stop the recursion

• The function should have a recursive case to continue the recursion

• Example: Factorial of a number using recursion

• Example: Fibonacci series using recursion

Python is a versatile programming language known for its simplicity and readability. It supports multiple programming paradigms and has a vast standard library.

• Python features include dynamic typing, automatic memory management, and support for multiple programming paradigms like procedural, object-oriented, and functional programming.

• Python is known for its readability and simplicity, making it a popular choice for beginners and experienced developers alike.

• Python has a vast...read more

Variables are containers for storing data. Loops are used to iterate over a sequence of elements. OOPs is a programming paradigm based on objects and classes.

• Variables are used to store data in memory. They can be assigned different values and data types.

• Rules for naming variables: must start with a letter or underscore, can contain letters, numbers, and underscores, cannot start with a number.

• Loops are used to execute a block of code repeatedly. Types of loops include for lo...read more

self is a reference to the instance of the class and is used to access its attributes and methods.

• self is the first parameter of any method in a class.

• It is used to refer to the instance of the class within the class itself.

• self allows the instance to access its own attributes and methods.

• It is automatically passed when a method is called on an instance.

Lists are mutable in Python.

• Lists can be modified after creation, allowing for addition, removal, and modification of elements.

• Tuples, strings, integers, and floats are immutable in Python.

• Example: list_example = [1, 2, 3]; list_example[1] = 5 # modifies the list element at index 1 to 5.

Design a CRUD App with AYSNC and AWAIT Operations in Fast API

• Use FastAPI framework for building the CRUD operations

• Implement async and await keywords for asynchronous operations

• Utilize SQLAlchemy for database operations

• Include endpoints for Create, Read, Update, and Delete operations

The question covers libraries, APIs, and previous projects.

• Python has a vast collection of libraries for various purposes.

• API stands for Application Programming Interface and is used to interact with software applications.

• I have worked on projects involving web scraping, data analysis, and machine learning.

• In a previous project, I faced a challenge with data cleaning and had to use regular expressions to solve it.

Developed a sentiment analysis web app using Flask, NLTK and AWS

• Used Python to scrape Twitter data using Tweepy API

• Preprocessed data using NLTK library

• Trained a machine learning model using scikit-learn

• Deployed the app on AWS Elastic Beanstalk

• Implemented user authentication and authorization using Flask-Login

To import views in Django, you need to create a views.py file and import it in urls.py

• Create a views.py file in your Django app directory

• Define your views in the views.py file

• Import your views in urls.py using the 'from . import views' syntax

• Map your views to URLs in urls.py using the 'path()' function

Data structures are ways of organizing and storing data in a computer so that it can be accessed and used efficiently.

• Arrays - a collection of elements of the same data type

• Linked Lists - a collection of nodes that contain data and a reference to the next node

• Stacks - a collection of elements that follows the Last In First Out (LIFO) principle

• Queues - a collection of elements that follows the First In First Out (FIFO) principle

• Trees - a hierarchical data structure that consis...read more

Yes, we can change the order of a dictionary in Python.

• Use OrderedDict to maintain the order of insertion

• Sort the dictionary based on keys or values

• Convert the dictionary to a list of tuples and sort them

• Use the sorted() function to sort the dictionary

Lambda functions are anonymous functions that can be defined in a single line of code.

• Lambda functions are defined using the lambda keyword.

• They can take any number of arguments, but can only have one expression.

• They are often used as arguments for higher-order functions.

• Example: lambda x: x**2 defines a lambda function that squares its input.

Yes, I have experience working with various technology stacks.

• I have worked with Python, Django, Flask, React, Angular, and Node.js in my previous projects.

• I am comfortable adapting to new technologies and learning new stacks as needed.

• I have experience collaborating with cross-functional teams that use different technology stacks.

Python handles conditional statements using if, elif, and else keywords to control the flow of the program.

• Python uses if, elif, and else keywords to create conditional statements.

• Indentation is crucial in Python to determine the scope of the conditional statements.

• Example: if x > 5: print('x is greater than 5')

• Example: if x > 5: print('x is greater than 5') elif x == 5: print('x is equal to 5') else: print('x is less than 5')

Postman is a popular API development tool used for testing, documenting, and sharing APIs.

• Postman allows developers to send HTTP requests and receive responses from APIs

• It provides a user-friendly interface for creating and managing API requests

• Postman also offers features like automated testing, mock servers, and collaboration tools

• It supports various authentication methods and formats like JSON and XML

To build ourselves for technology needs, we need to constantly learn and adapt to new technologies and trends.

• Stay updated with the latest technologies and trends in the industry

• Attend conferences, workshops, and webinars to learn new skills

• Practice coding regularly and work on personal projects to improve skills

• Collaborate with other developers and participate in open source projects

• Read blogs, articles, and books related to technology

• Be open to learning new programming lang...read more

Find the sum of unique numbers in a list.

• Create an empty set to store unique numbers

• Loop through the list and add each number to the set

• Sum up the numbers in the set

I rate myself as an experienced Python developer with strong skills in various Python libraries and frameworks.

• I have worked on various Python projects and have a good understanding of the language syntax and concepts.

• I am proficient in using popular Python libraries such as NumPy, Pandas, and Matplotlib for data analysis and visualization.

• I have experience in developing web applications using Python frameworks such as Django and Flask.

• I am familiar with using Python for mach...read more

Python uses automatic memory management through garbage collection.

• Python uses reference counting to keep track of objects in memory.

• When an object's reference count reaches zero, it is deleted by the garbage collector.

• Python also uses a cyclic garbage collector to detect and delete circular references.

• Memory can be managed manually using the ctypes module.

• Python's memory management is efficient but can lead to performance issues with large datasets.

PEP stands for Python Enhancement Proposal. PEP8 is a style guide for Python code.

• PEP is a process for proposing and discussing new features and changes to Python.

• PEP8 is a style guide for Python code, covering topics such as naming conventions, indentation, and whitespace.

• PEP8 is not mandatory, but following it can make code more readable and consistent.

• Examples of PEP8 guidelines include using four spaces for indentation, using lowercase with underscores for variable names,...read more

Commonly used inbuilt functions of Python

• print() - prints output to console

• len() - returns length of an object

• range() - generates a sequence of numbers

• type() - returns type of an object

• str() - converts an object to string

• int() - converts a string or float to integer

• float() - converts a string or integer to float

• list() - creates a list

• dict() - creates a dictionary

• set() - creates a set

A global variable is a variable that can be accessed from any part of the program.

• Global variables are declared outside of any function or class.

• They can be accessed and modified from any part of the program.

• Using global variables can make the code harder to read and debug.

• Example: x = 10 (declared outside of any function or class)

Python code for multi threading

• Import the threading module

• Create a class that inherits from the Thread class

• Override the run() method in the class with the code to be executed in the thread

• Create instances of the class and start the threads using the start() method

Handling real-time errors in a web application

• Implementing proper error handling mechanisms such as try-except blocks

• Logging errors to track and troubleshoot issues

• Using monitoring tools like Sentry or New Relic to detect errors in real-time

Models in Django are Python classes that define the structure of the database tables.

• Models are used to create, read, update and delete data from the database.

• They define the fields and their types, relationships between tables, and constraints.

• Models can be created using the Django ORM (Object-Relational Mapping) or by writing SQL.

• Example: class Book(models.Model): title = models.CharField(max_length=100) author = models.ForeignKey(Author, on_delete=models.CASCADE)

• Models are...read more

Corestack is a cloud automation and orchestration platform that helps enterprises manage their cloud infrastructure.

• Corestack provides a unified dashboard for managing multiple cloud platforms.

• It offers automation and orchestration capabilities to simplify cloud management.

• Corestack also provides governance and compliance features to ensure security and regulatory compliance.

• Some of Corestack's customers include Wipro, HCL, and Tech Mahindra.

Reverse a dictionary in Python

• Create a new dictionary with values as keys and keys as values

• Use dictionary comprehension to create the new dictionary

• If there are duplicate values, use a list comprehension to create a list of keys

• Use the built-in function 'reversed' to reverse the order of the keys or values

I use Git for version control in my projects.

• I create a Git repository for the project

• I commit changes regularly with descriptive messages

• I use branches for new features or bug fixes

• I merge branches back into the main branch when ready

• I use tags to mark important milestones or releases

Authentication is the process of verifying the identity of a user or system.

• Authentication ensures that only authorized users have access to a system or application.

• It involves the use of credentials such as usernames and passwords, or other methods like biometrics.

• Examples of authentication include logging into a website or accessing a secure network.

• Authentication is often followed by authorization, which determines what actions a user is allowed to perform.

reang is not a recognized term in Python development.

• reang is not a Python keyword, module, or function.

• There is no known reference or documentation for reang in Python.

• It is possible that reang is a typo or a mispronunciation of another term.

A while loop is a control flow statement that allows code to be executed repeatedly based on a condition.

• The loop continues until the condition becomes false

• The condition is checked before each iteration

• The loop body must include a way to modify the condition to avoid an infinite loop

Wrapper class is a class that wraps around a primitive data type and provides additional functionality.

• Wrapper classes in Python include int, float, str, etc.

• They allow primitive data types to be used as objects.

• Example: int is a wrapper class for integer data type.

Open source refers to software that is freely available for anyone to use, modify, and distribute.

• Open source software allows for collaboration and transparency in development.

• Examples of open source software include Linux, Apache, and Mozilla Firefox.

• Open source licenses typically allow for the free use, modification, and distribution of the software.

• Open source communities often provide support and resources for users and developers.

Python is a high-level programming language known for its simplicity and readability.

• Python is an interpreted language, meaning it does not need to be compiled before running.

• It has a large standard library that provides many pre-built functions and modules.

• Python supports multiple programming paradigms, including procedural, object-oriented, and functional programming.

• It is widely used in web development, data analysis, artificial intelligence, and scientific computing.

• Pytho...read more

Namespace is a container that holds identifiers (names) used to avoid naming conflicts.

• Namespace is created at different moments and has different lifetimes.

• Python implements namespaces as dictionaries.

• There are four types of namespaces in Python: built-in, global, local, and non-local.

• Namespaces can be accessed using the dot (.) operator.

• Example: 'import math' creates a namespace 'math' that contains all the functions and variables defined in the math module.

Program to generate a particular series

• Define the series pattern

• Use loops to generate the series

• Store the series in an array

• Print the array

for loop is used for iterating over a sequence while while loop is used for executing a block of code repeatedly as long as a condition is true

• For loop is used when the number of iterations is known, while loop is used when the number of iterations is unknown

• For loop is more concise and readable for iterating over sequences like lists, while loop is more flexible for complex conditions

• Example: for i in range(5): print(i) - prints numbers 0 to 4, while example: x = 0; while x ...read more

A function in Python is defined using the 'def' keyword followed by the function name and parameters.

• Use the 'def' keyword followed by the function name and parameters enclosed in parentheses.

• Indent the function body to define the code block.

• Use the 'return' statement to return a value from the function.

• Example: def greet(name): print('Hello, ' + name)

• Example: def add_numbers(a, b): return a + b

Convert two lists into a dictionary.

• Use zip() function to combine the two lists.

• Pass the combined list to dict() function to create a dictionary.

• Use a loop to iterate through the dictionary and print the key-value pairs.

Function to determine if a number is prime or not.

• Check if the number is less than 2, return False if so

• Iterate from 2 to the square root of the number, checking for divisibility

• If no divisors found, return True (number is prime)