Python is undoubtedly one of the most popular programming languages. And due to this overwhelming popularity and its utility in the IT industry, Python stays extremely relevant in job requirements in development for almost any domain like back-end, front end and even for scripting too. And this also makes it a prime subject for job interviewers to test candidates on.
That is why we are coming up with a list of 21 Essential Python Interview Questions to help you with your job interviews for all the roles in domains like back-end, front-end, etc.
These questions will cover the ground on all the fronts at a basic level for your next job interview. So, browse through this list of questions and answers and brush up your knowledge to bag the next job offer!
- Python is a programming language that is object-oriented in nature and supports multiple platforms.
- Python finds its application across various domains like data science, artificial intelligence, machine learning & deep learning, etc.
- Libraries available for Python are diverse and provide a lot of functionalities to developers.
- Python is convenient for beginners to start off their career in programming as it has much easier syntax compared to other languages.
List of 21 Python Interview Questions for 2022
1. What is Python?
It is a general-purpose, high-level, object-oriented language that runs just the same irrespective of the underlying platforms like Windows, Linux, UNIX, and Mac. It is a mainstream language for data science, machine learning, and artificial intelligence specialized fields.
2. What are the Features of Python
- Python has simple syntax in comparison to other languages, hence making it easier for beginners, and has an intuitive code structure to help developers to write and debug it.
- It is compatible with various platforms like Windows, Mac, Linux, Raspberry Pi, etc.
- It is also free and open-source.
- It can be used across different languages.
- Python is an object-oriented language and thus, it supports concepts of classes.
3. What are Keywords in Python?
Keywords are reserved words in Python which are used as identifiers, variable names, or function names. These keywords help in defining the structure and syntax of the language.
In Python, there are a total of 33 keywords in Python 3.7 which might change in the subsequent versions. The list of all the Python keywords is given below:
4. What are Python namespaces? Why are they used?
A namespace in Python means that it ensures the object names are always unique and can be used without any issue or conflict. By defining these namespaces as dictionaries, Python implements this functionality. By using ‘name as key’ mapping to a required ‘object to value’, multiple namespaces are assigned to the same name mapping separate objects. A few instances of namespaces are as follows-
- Local Namespace includes local names inside a function. The namespaces are temporarily created for function calls and it then gets cleared when these functions return values.
- Global Namespace includes names from different imported packages that are used in the current project. Namespaces are created as the packages are imported in the code and last until the execution of the code.
- Built-In Namespace includes built-in functions of core Python and built-in names for different types of exceptions.
5. What are Python Literals? Explain some different Literals.
Python Literals signifies the data that is provided in a variable or constant. The various types of Python Literals include:
- String Literals – It is a sequence of characters enclosed in codes. There can be single, double, and triple strings based on the number of quotes used. Character literals are single characters enclosed with single quotes or double quotes.
- Numeric Literals – These are the immutable type and it is broken down into three types- Integer, Complex, and Float.
- Boolean Literals – These can have one of two values- True or False which signifies ‘1’ and ‘0’ respectively.
- Special Literals – These are used to classify fields that aren’t created. It is signified with the value ‘none’.
6. what are Python Functions?
Python functions are nothing but blocks of code that are organized and ready to be re-used to perform single or multiple related events. Functions are crucial to provide better modularity for applications that reuses a higher degree of coding. Python also has a number of built-in functions like print(). User-defined functions can also be used the same way as built-in functions are used.
7. What is recursion in Python?
Recursion is a concept where a function calls itself one or more times from its own code block/body. The implementation of this concept in a program must ideally have a method of termination of the recursion. If not done, it leads to the infinite loop problem.
8. What are Python modules and packages?
Modules are ways to structure a program as each Python program file is actually a module. This module imports other attributes and objects. The folder of the program is a package of modules. And a package can have modules/subfolders.
9. What is Pandas Python library?
Pandas is an open-source Python library that comes with a diversely rich set of data structures for data operations. It also has a cool feature set that provides a fit for every data operation role.
Be it academics or solving complex business problems, Pandas can deal with all these use-cases easily. It can also be used with a large variety of files and proves to be one of the best tools to have expertise in.
10. What are Pandas Dataframes?
A Pandas data frame is a data structure in Pandas that is mutable in nature. Pandas have support for heterogeneous data which is arranged across two axes (columns and rows).
Reading files into Pandas:
import pandas as pd
Over here, df is a Pandas data frame. The read_csv() is used to read comma-delimited files as a data frame in Pandas.
11. What is a dictionary in Python? Provide an example of a Python dictionary.
A Python dictionary is a collection of items in no pre-ordained order. These dictionaries are written in curly braces with key-value pairs. Dictionaries are created and optimized for value retrieval for known keys by developers as per their applications.
12. What is inheritance in Python and what types of inheritance is supported by Python?
Since Python is based on an object-oriented programming paradigm, Python classes have the ability to inherit the attributes and properties of another Python class. This process is called inheritance. Inheritance facilitates the code reusability feature. The source class that is being inherited is called a superclass or parent class. And the class that inherits the properties of the superclass is called derived or child class.
The supported types of inheritance in Python:
- Single Inheritance – When a child class inherits only one superclass.
- Multiple Inheritance – When a child class inherits multiple superclasses.
- Multilevel Inheritance – When a child class inherits a superclass and then another class inherits this derived class forming a ‘parent, child and grandchild’ class structure.
- Hierarchical Inheritance – When a superclass is inherited by multiple derived classes.
13. How does pass, continue and break work in Python?
These statements help in changing the phase of execution from normal control flow. This is the reason why these statements are termed as loop control statements.
Pass – This statement helps to write the code syntactically and lets the control skip the execution. It is considered as a null operation as nothing happens when this statement is executed.
Continue – This statement helps force the execution of the next iteration when a given condition meets.
Break – This statement lets you terminate the loop/statement and passes the control onto the next statement.
14. What is Polymorphism in Python?
Polymorphism is the ability of the code to take multiple forms. For instance, if a parent class has a method named ABC, then the child class can also have a method with the same name as ABC. It will have its own variables and parameters with this method as well.
15. How does Python Flask handle database requests?
Python Flask supports database-powered applications called RDBS. A system like this requires the creation of a schema, which further requires piping of the schema.sql file into sqlite3 command. Python developers are required to install the sqlite3 command to create or initialize the database in Flask.
Python Flask allows request for a database in these ways:
- before_request() – These are called before a request and pass no arguments.
- after_request() – These are called after a request and pass the response which is sent back to the client.
- teardown_request() – These are called in scenarios when an exception is raised and responses are not guaranteed. They are invoked after the response has been constructed. These methods aren’t allowed to change the request and their values are not considered.
16. How does Multithreading work in Python?
There is a multithreading package in Python but is normally considered as a “not-so-good” practice to import it since it causes higher code execution time.
Python has a constructor named Global Interpreter Lock or GIL. GIL makes sure that only one of your “threads” can execute at one time. This process ensures that a thread acquires the GIL, does a small fraction of the work, and passes the GIL to the next available thread.
All of the above processes happen quite quickly and it might seem as if all of the threads are working parallelly. But in truth, the execution happens sequentially using the same CPU core for the work at hand.
17. Write a program in Python to do a Bubble Sort.
n = len(x)
# Traverse through every array elements
for i in range(n-1):
for j in range(0, n-i-1):
if x[j] > x[j+1] :
x[j], x[j+1] = x[j+1], x[j]
# Test code block to check functionality
arr = [79, 47,24, 52, 81, 62,13]
print (“Sorted array is:”)
for i in range(len(arr)):
print (“%d” %arr[i]),
The output is-
13, 24, 47, 52, 62, 79, 81
18. Write a program in Python to produce a Fibonacci series.
Fibonacci series refers to a series where the elements are the sum of two elements just before it.
#This is a function for nth Fibonacci Number
#Check if input 0, and prints incorrect input
if x < 0:
elif x == 0:
elif x == 1 or x == 2:
return Fibonacci(x-1) + Fibonacci(x-2)
#Invocation of Test Code
19. What is enumerate() in Python?
In Python, enumerate() is a built-in function used for the assignment of indices to each item of iterable objects. It includes a loop on the iterable objects while keeping track of the current items and returns the object in an enumerable form. This returned object can be used in a for loop to convert it into a list by using the list() method.
Let’s take the collection of names in a week and number them (Sunday, Monday, Tuesday,…, Saturday). So, first, we declare the variable ‘x’ which enumerates the numbers while ‘y’ prints the number of months in the list.
#using for loop over a collection
Week = [“Sunday”,”Monday”,”Tuesday”,”Wednesday”,”Thursday”,”Friday”, “Saturday”]
for x, y in enumerate (Week):
20. What is __init__?
In Python, __init__ is a method or constructor. This is automatically called to allocate memory when a new object or instance of a class is created. Typically, all the classes have the __init__ method.
An example of it would be:
# Defining a class
def __init__(self, namef, namel, age, section):
self.firstname = namef
self.lastname = namel
self.age = age
self.section = section
# creating a new object
stu = Student(“John”, “Doe”, 22, “A2”)
21. How to copy an object in Python?
In Python, the assignment statement or = operator creates a link between the existing object and the target variable name. And so, if you want to create copies of an object in Python, you have to use the copy Python module.
There are two types of copy:
- Shallow copy – It does a bit-wise copy of the object. The copied object will have an exact replica of the values held in the original object. And if any of the values are referenced to other objects, only the reference addresses of the object will be copied.
- Deep copy – It copies all the values recursively from source to target object. This will duplicate the objects too which were referenced by the source object.
I hope that you find these 21 Essential Python Interview Questions to be helpful. The above questions coupled with your own hands-on practice will help you to crack any technical Python interview in the future.
Once the basics are all hashed out, you should only be practising so that when the interviewer asks you questions, you should be able to write and execute codes in your mind.
Python provides a good career trajectory if you devote yourself to perfect the language. If you want to learn to pick up Python for better job opportunities, you should also consider exploring the highest-paying languages to learn.
Frequently Asked Questions (FAQs)
Can I teach myself Python?
Yes, it is very much possible to teach yourself Python on your own. There is a wide variety of self-tutoring resources available on the web for you to teach yourself Python. These Python resources come with bundled projects and tasks to test your learning along the way too. But there are many gaps in self learning and you might not find the right material online for free. Hence an affordable beginner course is recommended.
Should I learn Python first or C++?
Python is much easier to learn than C++. It also has better practical uses than C++. But C++ is a lower-level language. It teaches about computing and programming at a much base level.
How do I start coding?
To start off with coding, you have to take these steps. You can start working on a simple project. For that, you need to set up an IDE and start coding certain functionalities as required. You can read various books on Python and try to run those codes to understand how the Python compiler works.
Why is Python so popular?
Python is popular because it is highly productive in comparison to its counterpart programming languages like C++, Java, etc. Python is also very popular due to its code readability, English-like commands which makes Python coding way easier and efficient.
Does Python coding require maths?
Python programming does not really require much maths as it is perceived to be. But it is important to understand the concept of maths which provides certain Python coding foundations.