Top 25 Python Interview Questions and Answers

by Alex
Top 25 Python Interview Questions and Answers

You have an interview for a Python developer position waiting for you, and do you want to know what questions and discussions you will go through? Before you go, it’s best to have at least a general idea of the types of questions that will be asked in a Python interview so that you can prepare your answers. That said, Python is a very important tool in any developer’s arsenal. To help you, I’ve created the best Python interview question and answer guide to understand the depth and real purpose of Python. In addition to these questions, you will also probably be given code snippets that you will have to read to determine the resulting value (or lack thereof). Such tasks are impossible to predict, and their success will depend on your programming experience. Let’s start with the most popular Python interview questions and answers.

Python 2021 Interview Questions and Answers

1) What is the difference between a module and a package in Python? Each Python program file is a module that imports other modules as objects. Thus, a module is a way of structuring your program. A folder containing a Python program is called a module package. 2) What are the built-in types available in Python? This is one of the most common interview questions. Python has changeable and immutable built-in types. Variable types include:

  • Lists,
  • Sets,
  • Dictionaries.

Non-modifiable types are:

  • Strings,
  • Tuples,
  • Numbers.

3) What is a lambda function in Python? A lambda is often used as an inline function and is a single anonymous functional expression. It is used to create a new function object and return it at runtime. A lambda is an anonymous function in Python that can take an unlimited number of arguments and can have any number of parameters. However, a lambda function can have only one expression or instruction. It is usually used in situations where an anonymous function is required for a short period of time. Lambda functions can be used in one of two ways: An example of a lambda function:

a = lambda x,y : x+y
print(a(5, 6))
# Output: 11

4) What does namespace mean? A namespace is a system of names that is used to ensure that all objects in a program are named uniquely to avoid possible conflicts. In Python, these namespaces are implemented as dictionaries with name as the key and object as the value. As a result, different namespaces can give their objects the same name. Below are three types of namespaces in Python:

  • Local namespace – includes local names within a function. The local namespace is temporarily created when the function is called and cleared on return from the function.
  • Global namespace – consists of the names of the various imported packages/modules that are currently in use in the project. The global namespace is created when a package is imported into a script, and it is available until the script finishes executing.
  • Embedded namespace – this includes built-in Python functions and embedded names for different types of exceptions.

5) Explain the difference between a list and a tuple? A list is modifiable, while a tuple is not. Tuples can be hashed, as in the case of keys for dictionaries. 6) What is the difference between pickling and unpickling? Any Python interview Q&A guide wouldn’t be complete without this question. In Python, the pickle module takes any Python object, converts it to a string representation, and offloads it to a file using the dump function. Such a process is known as pickling. The pickle.dump() function is used for this process. On the other hand, the process of extracting the original Python object from the stored string representation is called unpickling. The pickle.load() function is used for this process. 7) What are decorators in Python? A Python decorator is some update to the Python syntax made to change functions more easily. 8) The difference between generators and iterators? In Python, iterators are used to enumerate a group of elements (for example, in a list).

Generators are a way of implementing iterators. They use yield to return an expression from a function, but otherwise a generator behaves like a normal function. 9) How do I convert a number to a string? One of the most common questions in an interview. We can use the built-in str() function. For an octal or hexadecimal representation of a number, we can use other built-in functions like oct() or hex(). 10) How is the // operator used in Python? Using the // operator between two numbers gives the quotient when dividing the numerator by the denominator. It is also called the division operator without a remainder. 11) Does Python have a Switch or Case instruction like in C? No. However, we can create our own Switch function and use it. 12) What is the range() function and what are its parameters? The range() function is used to create a list of numbers. Only integers are allowed, so the arguments passed in can be either negative or positive. The following parameters are allowed:


Where “stop” is the number of integers to generate, starting with 0. Example: list(range(5)) == [0,1,2,3,4] Other parameters: range([start], stop[, step]):

  • Start: specifies the first number in the sequence.
  • Stop: specifies the upper limit for the sequence.
  • Step: increment factor in the sequence.

13) How is %s used? %s is a format specifier that converts any value to a string. 14) Does a Python function have to return a value? No 15) Does Python have a main() function? Yes, there is. It is executed automatically whenever we run the script. If you want to change this natural order of things, use the if statement. 16) What is GIL? GIL or Global Interpreter Lock is a mutex used to limit access to Python objects. It synchronizes threads and prevents them from running simultaneously. 17) What method was used before the “in” operator to check for a key in the dictionary? The has_key() method. 18) How do you change the data type of a list?

To turn a list into a tuple, we use the tuple() function. To turn it into a set, we use set(). To turn it into a dictionary – dict(). To turn it into a string – join(). 19) What are the key features of Python? This is one of the common interview questions. Python is an open-source, high-level general-purpose programming language. Because it is a general-purpose programming language, and it comes with a large set of libraries, you can use Python to develop almost any type of application. Some of its key features are:

  • Interpreted,
  • With dynamic typing,
  • Object-oriented,
  • English-language syntax.

20) Explain memory management in Python. In Python, the memory manager takes care of memory management. It allocates it as space in the heap, where all Python objects and data structures are stored. There are 4 built-in data structures in the language. This space is not directly available to the programmer. However, the basic API allows the developer to access some tools for writing code. In addition, Python has a built-in garbage collector that frees unused memory from the heap space. 21) What is PYTHONPATH? PYTHONPATH is an environment variable that is used to include additional directories when a module/package is imported. Each time a module/package is imported, PYTHONPATH is used to check if the added modules are in existing directories. Normally, the interpreter uses PYTHONPATH to determine which module to load. 22) Is Python case-sensitive? A programming language is considered case-sensitive if it distinguishes between identifiers such as “myname” and “Myname”. Simply put, it cares whether the characters are lowercase or uppercase. Let’s look at an example:

>>> myname="John"
>>> myname
Traceback (most recent call last):
File "", line 1, in
NameError: name 'Myname' is not defined

The occurrence of the NameError means that Python is case-sensitive. 23) Explain the use of help() and dir(). In Python, the help() function is used to display documentation on modules, classes, functions, keywords, and so on. If help() receives no parameters, it runs an interactive help utility on the console. The dir() function returns a valid list of attributes and methods of the object to which it is called. Because the function is designed to retrieve the most relevant data (instead of displaying complete information), it behaves differently with different objects:

  • For modules/libraries dir() returns a list of all the attributes contained in that module.
  • For class objects, dir() will return a list of all valid attributes and base attributes.
  • When no parameters are passed to it, dir() will return a list of attributes in the current scope.

24) What are Python modules? Name some of the most commonly used built-in modules in Python? Python modules are files containing Python code that are either function classes or variables. Modules are Python files with a .py extension. They can include a set of functions, classes, or variables that are defined and implemented. You can import and initialize a module using the import instruction. By studying the Python manual, you can learn more about modules in Python. Here are some of the most commonly used built-in modules in Python: Operating Systems

  • os,
  • sys,
  • math,
  • random,
  • datetime,
  • JSON.

25) Explain what “self” means in Python. In Python, “self” is a keyword used to define an instance or object of a class. Unlike Java, where self is optional, in Python it is used as the first parameter. Self helps distinguish the methods and attributes of a class from its local variables. The self variable in the __init__ method refers to the created object or instance, whereas in other methods it points to the object or instance whose method was called.

Want to get a Python developer job?

Then you need to run the following algorithm:

  1. Enroll in a course from Skillbox “The Python Developer Profession”;
  2. Meet an individual mentor who will help you create your first Python program and get real development experience;
  3. Go through 7 blocks of training with different levels of complexity, the knowledge of which can be equated to a year of work;
  4. Defend your diploma in front of real customers. It’s not hard, as by the end of the training you will have 2 projects on Github and a deep understanding of Python;
  5. Work with experienced HR professionals to build a resume and prepare for interviews;
  6. Be interviewed for jobs selected for you by Skillbox Career Center.

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