40 Most Common Interview Questions On Python

Here are 40 common Python interview questions along with their answers. These questions cover various aspects of Python, including basic concepts, data structures, libraries, and more advanced topics.

1. What is Python? Python is a high-level, interpreted, and general-purpose programming language. It was created by Guido van Rossum and first released in 1991. Python is known for its readability, simplicity, and extensive standard library.
2. What are the key features of Python? Some key features of Python include:
   • Easy-to-read syntax
   • Dynamically typed
   • Object-oriented, procedural, and functional programming paradigms
   • Extensive standard library
   • Cross-platform compatibility
   • Strong community support
3. What are Python’s built-in data types? Python’s built-in data types include:
   • Numeric: int, float, complex
   • Sequence: str, list, tuple
   • Mapping: dict
   • Set: set, frozenset
   • Boolean: bool
   • NoneType: None
4. What is the difference between a list and a tuple in Python? Lists are mutable, ordered sequences of elements, while tuples are immutable, ordered sequences of elements. Lists are defined using square brackets [], while tuples are defined using parentheses ().
5. What is a dictionary in Python? A dictionary is an unordered collection of key-value pairs, where each key is unique. Dictionaries are mutable and are defined using curly braces {}.
6. What is a set in Python? A set is an unordered collection of unique elements. Sets are mutable and can be created using the set() constructor or by using curly braces {} with comma-separated elements.
7. What is the difference between a mutable and an immutable object in Python? Mutable objects can be modified after they are created, while immutable objects cannot. Examples of mutable objects include lists, dictionaries, and sets. Examples of immutable objects include strings, tuples, and frozensets.
8. What are Python’s control structures? Python’s control structures include:
   • Conditional statements: if, elif, else
   • Looping statements: for, while
   • Loop control statements: break, continue
   • Exception handling: try, except, finally, raise
9. What is a function in Python? A function is a block of reusable code that performs a specific task. Functions can accept input arguments and return a value. Functions are defined using the def keyword.
10. What is a lambda function in Python? A lambda function is an anonymous, inline function that can accept any number of arguments but can only have a single expression. Lambda functions are defined using the lambda keyword.
11. What is the difference between a global and a local variable in Python? A global variable is accessible throughout the entire program, while a local variable is only accessible within the function or block of code where it is defined.
12. What is a module in Python? A module is a file containing Python code, usually with a .py extension. Modules can define functions, classes, and variables, and can be imported into other Python scripts using the import statement.
13. What is the purpose of the __init__ method in a Python class? The __init__ method is a special method called a constructor. It is automatically called when a new instance of a class is created. The __init__ method is typically used to initialize instance variables and perform any setup required for the object.
14. What is inheritance in Python? Inheritance is a way to create a new class that is a modified version of an existing class. The new class, called the subclass, inherits attributes and behaviors from the existing class, called the superclass.
15. What is a generator in Python? A generator is a special type of iterator that yields values using the yield keyword instead of returning them with the return keyword. Generators are defined using the def keyword, like regular functions, but they maintain their state between calls, allowing them to produce a sequence of values over time.
16. What is the difference between range and xrange in Python? In Python 2, range creates a list of numbers, while xrange creates an xrange object, which is an iterator that generates numbers on-the-fly. In Python 3, the xrange function has been removed, and the range function now behaves like xrange in Python 2, returning a range object that generates numbers on-the-fly.
17. What is list comprehension in Python? List comprehension is a concise way to create a list using a single line of code. It consists of an expression followed by a for clause, and optionally one or more if clauses. The expression is evaluated for each item in the sequence specified in the for clause, and the result is a new list.
18. What is the Global Interpreter Lock (GIL) in Python? The Global Interpreter Lock (GIL) is a mutex that protects access to Python objects, preventing multiple threads from executing Python bytecodes concurrently in the same process. The GIL is necessary because CPython’s memory management is not thread-safe. However, the GIL can limit the performance of CPU-bound and multithreaded programs in CPython.
19. What is the difference between == and is in Python? The == operator compares the values of two objects for equality, while the is operator compares the identity of two objects, meaning they must be the same object in memory.
20. What is the enumerate function in Python? The enumerate function is a built-in function that takes an iterable as an argument and returns an iterator that produces tuples containing the index and the corresponding element from the iterable.
21. What is the zip function in Python? The zip function is a built-in function that takes two or more iterables as arguments and returns an iterator that generates tuples containing elements from the input iterables, where the first elements are paired together, the second elements are paired together, and so on.
22. What is the *args and **kwargs syntax in Python? The *args syntax in a function signature allows the function to accept a variable number of positional arguments, which are passed as a tuple. The **kwargs syntax allows the function to accept a variable number of keyword arguments, which are passed as a dictionary.
23. What is a context manager in Python? A context manager is an object that defines a method for setting up a context, such as opening a file or acquiring a lock, and a method for tearing down the context, such as closing the file or releasing the lock. Context managers are typically used with the with statement to ensure that resources are properly acquired and released.
24. What is the pickle module in Python? The pickle module is a built-in module that provides a way to serialize and deserialize Python objects while preserving their structure and relationships. The pickle module can handle most Python data types, including custom classes and functions.
25. What is the os module in Python? The os module is a built-in module that provides a way to interact with the operating system, such as creating and deleting files, executing commands, and managing processes.
26. What is the re module in Python? The re module is a built-in module that provides support for regular expressions, which are a powerful tool for text processing and pattern matching.
27. What is the collections module in Python?The collections module is a built-in module that provides specialized container data types, such as namedtuple, deque, Counter, OrderedDict, and defaultdict.
28. What is the itertools module in Python? The itertools module is a built-in module that provides a collection of fast, memory-efficient tools for working with iterators, such as chain, cycle, groupby, and various combinatoric generators.
29. What is the functools module in Python? The functools module is a built-in module that provides higher-order functions and tools for working with functions, such as partial, reduce, lru_cache, and total_ordering.
30. What is the json module in Python?The json module is a built-in module that provides a way to encode and decode JSON (JavaScript Object Notation) data, which is a lightweight data interchange format.
31. What is the csv module in Python? The csv module is a built-in module that provides a way to read and write data in CSV (Comma Separated Values) format, which is a common format for exchanging data between applications.
32. What is the socket module in Python? The socket module is a built-in module that provides a way to create and manage network sockets, which are endpoints for sending and receiving data over a network.
33. What is the threading module in Python? The threading module is a built-in module that provides a way to create and manage threads, which are lightweight, concurrent units of execution within a single process.
34. What is the multiprocessing module in Python? The multiprocessing module is a built-in module that provides a way to create and manage processes, which are independent units of execution that run in separate memory spaces.
35. What is the asyncio module in Python? The asyncio module is a built-in module that provides a framework for writing asynchronous, non-blocking code using coroutines, which are a way to write concurrent code that looks and behaves like synchronous code.
36. What is the numpy library in Python? NumPy is a third-party library for numerical computing in Python. It provides a high-performance, multidimensional array object and tools for working with arrays, such as mathematical, logical, and statistical operations.
37. What is the pandas library in Python? Pandas is a third-party library for data manipulation and analysis in Python. It provides data structures such as Series and DataFrame, which are designed for handling and analyzing large, structured datasets.
38. What is the matplotlib library in Python? Matplotlib is a third-party library for creating static, interactive, and animated visualizations in Python. It provides a flexible and powerful API for creating various types of plots and charts.
39. What is the scikit-learn library in Python? Scikit-learn is a third-party library for machine learning in Python. It provides a wide range of algorithms for classification, regression, clustering, dimensionality reduction, and model selection, as well as tools for preprocessing data and evaluating model performance.
40. What is the tensorflow library in Python? TensorFlow is a third-party library for machine learning and deep learning in Python. It provides a flexible and efficient platform for defining, training, and deploying machine learning models, including neural networks, on various types of hardware, from CPUs to GPUs and TPUs.