Python Interview Questions You Might Be Asked

Python Interview Questions You Might Be Asked Python is one of the most popular programming languages in the world. It's used by tech giants like Google, Reddit, and Yahoo. The Python Programming language was created by Guido van Rossum in 1991 and has since become the most widely used language on GitHub. If you're applying to any technology-related job or are working in the tech industry and don't know Python, it's time to learn!

5 Most Frequently Asked Python Interview Questions

  1. How would you write a Python program to find a word in another Python program that contains three characters?
  2. Given a list of sorted numbers, how would you calculate its average?
  3. What's your understanding of looping over every element in an array and incrementing an accumulator variable each time?
  4. What are some differences between lists and tuples?
  5. Explain how regex works and give some examples of its use cases?

Given a list of sorted numbers, how would you calculate its average?

With Python, I would use sum to find total of all numbers in list and then take average by dividing it by number of numbers. Following is my code: >>> a = [10, 20, 30] >>> print(sum(list)) 50 >>> print(Average is:, (sum(list)/len(list))) Average is: 15.0 Given a string s containing only lowercase letters, how would you count its occurrences of consecutive pairs of letters 'AB'? : With Python, I can write a loop to do it.

How would you write a Python program to find a word in another Python program that contains three characters?

Python programming language allows you to define variables, assign values to them and perform operations. To write a program in Python we need to follow three steps: defining variables, declaring code blocks and writing Python statements. All these three elements are denoted by different operators. The two most important operators for writing programs in Python are = (equal) and : (colon). The equal operator is used for assigning values to variables while colons are used for executing functions and blocks of code.

Explain how regex works and give some examples of its use cases?

Regular expressions (or regex) is a programming language that can be used to search for patterns in strings. It’s commonly used by programmers to validate user input, test lines of code, and perform data transformations.

What's your understanding of looping over every element in an array and incrementing an accumulator variable each time?

If you’re asked, What’s your understanding of looping over every element in an array and incrementing an accumulator variable each time? you’ll want to talk about how to loop through a collection and modify its elements.

What are some differences between lists and tuples?

  • Lists and tuples are two ways of writing data in Python.
  • A list is an ordered collection of items, or elements.
  • It may contain any kind of Python object: numbers, strings, lists and dictionaries.
  • The number of elements in a list is variable.
  • Lists are enclosed in square brackets with each element separated by a comma. Here’s an example: [1, 2, 3].
  • A tuple is also an ordered collection of items but can only contain specific types such as integers or strings.

How is Python different from Java?

  • One of the key differences between Python and Java is that while Java is a statically typed language, Python is a dynamically typed language. As such, Python doesn't rely on types to determine how your program runs.
  • The runtime environment can figure out type compatibility instead of compile-time; hence, you don't need to define variables with data types in Python code.
  • It helps to save time for programmers and reduces errors too. But it also means that static typing isn't possible in Python, as there aren't strong checks against typos or other errors when compiling.
  • A more significant difference lies in their syntaxes—the development teams have approached writing applications from different angles.
  • They have different programming styles that influence things like speed and support for multiple platforms.
  • For example, Java was developed by Sun Microsystems from 1992 onwards to create software components that could incorporate into larger systems built using any technology; hence its name: Java platform. Also known as OOP languages (object-oriented programming), most of today's languages use similar techniques since C++ inspired them—Java was no exception here.

What does it mean to iterate in Python?

  • In Python, iteration means reading a sequence of objects and making changes to each object one by one.
  • For example, in code, you can iterate over a list using a for loop: my_list = [0, 1, 2] for item in my_list: print(item) This prints 0, then 1 then 2, as shown below: A related concept is that of generator expressions.
  • A generator expression creates an iterator (which we just talked about), allowing us to iterate on something without explicitly designing it as a list or other data structure.

How do you deal with errors in Python?

The Python interpreter (called Python) accepts any legal Python program and interprets it. If it can, it will carry out its instructions; if not, it will display an error message and quit. These messages may seem cryptic at first, but there are many facilities for getting more information about what went wrong.

Error messages tend to be designed so that if you understand them, you'll have a good idea of how to fix your program.

Is Python scalable?

Python programming is a widely-used general-purpose programming language applied to many different use cases. It has been shown to work quite well for scalable projects and large-scale applications, including operating systems and web servers.

However, Python is often not considered suitable for handling concurrency at scale (for example, hundreds of thousands of requests coming in) or crunching high volumes of data. These things are left to other programming languages such as Java, Go or Node.js.

Why should I use Python over C++ or C#?

Python programming is one of those languages that you wonder why it wasn't something you created with earlier once you start using it. It's a good language for beginners, and experts can get a lot of mileage out of it.

C++ and C# are powerful tools to have in your belt, but they are much more complex than Python, especially for pointers and memory management. The choice between them will ultimately depend on what kind of development experience you already have under your belt.

If C++ or C# is what you know best, then stick with it; if not, take advantage of Python's easy-to-use syntax and dynamic typing to speed up development time.

Why do we use Python?

Python is a highly readable language, which means it's easy to grasp what a program does quickly.

It also makes Python an excellent choice for beginners and experts alike. When used in conjunction with tools like Jupyter Notebooks, Python can be a great tool for prototyping ideas and sharing code. For instance, check out our Intro to Data Science in Python Tutorial.

What are the applications of Python?

  • Python is a general-purpose programming language.
  • Its design philosophy emphasizes code readability, and its syntax allows programmers to express concepts in fewer lines of code than would be possible in languages such as C++ or Java.
  • The language provides constructs intended to enable clear programs on both a small and large scale. It supports multiple programming paradigms, including object-oriented, imperative and functional programming or procedural styles.
  • If you have programmed using different programming languages before, it's not going to take much time for you to learn Python.
  • This brief tutorial shows some of the most frequently asked questions in interviews for Python positions.

What are the advantages of Python?

  • The first advantage is that Python is an interpreted language; you don't need to compile your source code before running it.
  • The second advantage of Python is that it has dynamic types. Dynamic typing allows you to store objects without explicitly stating what type they are (for example, if a variable can hold integers, strings or lists).
  • The third advantage of Python is its large standard library.

What do you mean by Python literals?

A literal is a notation representing a fixed value in the source code.

In Python, there are several kinds of literal: strings, numbers, Booleans, and None. The difference between these literals is their type: each corresponds to a particular object type. String literals are written with either single or double quotes; other literals are written without special punctuation marks.

What type of Programming language is Python?

  • Python language is a high-level, general-purpose programming language that can apply to many different kinds of software development.
  • It also offers strong support for integration with other languages and tools, comes with extensive standard libraries, and can be learned quickly. Python's simple, easy-to-read syntax emphasizes readability and reduces the cost of program maintenance.
  • The language features automatic memory management and a dynamic type system.

How is Python an interpreted language?

  • It may be asked to test your knowledge of Python.
  • If you appear for an interview related to Python, you must completely understand its features. One of its features is that it is an interpreted language.
  • It means that when a code written in Python language is executed, it can be read and understood by humans and machines.

What is namespace in Python?

A namespace is an area of memory used by Python to keep track of objects and variables. Every name you define in a module gets its namespace inside that module's memory area, so different modules' names do not interfere with each other. It means that Python does not have to worry about two different names meaning two different things when they occur together in your code.


The PYTHONPATH variable is a list of directories separated by colons that python checks for imported modules. For example, if your PYTHONPATH is set to /usr/local/lib/python2.7/site-packages, then whenever you import a module from any directory inside /usr/local/lib/python2.7/, Python will try to load it from there first and will only look elsewhere if it doesn't find it.

What are python modules?

Python modules are collections of Python definitions and statements, usually stored in a file, imported into another Python program. Modules are used to break programs into multiple files, although, in recent years, larger projects have tended to put all code into one file for simplicity. In addition to organizing code, modules define an interface that software components can implement to specify how to integrate them.

What are local variables and global variables in Python?

  • A variable is a name that can assign to anything with a value. The most common data types in Python are numbers and strings.
  • There are two categories of variables in Python: local variables and global variables. Local variables are only accessible inside functions, whereas global variables are available everywhere in your program.
  • However, you can also create local variables inside functions if you wish to have private data for that function without affecting other parts of your program.

Explain what is Flask and what its benefits are?

  • Flask is a micro web framework for Python.
  • It is based on Werkzeug and Jinja 2 and can be used with MongoDB, SQLAlchemy and other databases.
  • Flask does not enforce any particular development style but favours a model–view–controller (MVC) approach. What makes Flask stand out are its extensions, of which there are many, such as Flask-WTF or flask-sqlalchemy.
  • Extensions provide extra functionality, mostly focused on Template engines and databases. The extension mechanism is easy to use; it consists of writing a small plugin that exports at least two functions: initialization and register routes/endpoints.
  • These plugins have access to some global variables that cooperate well if desired.

Is Django better than Flask?

  • Interviewers want to gauge your level of expertise with Django, so if you're not familiar with Flask, do a little research before you get in front of them.
  • Both frameworks are commonly used for Python web development, and it's important to understand which one(s) might be best suited for your particular project.
  • Most Python developers will tell you that both frameworks are great for beginners and experts alike—but that doesn't mean there aren't differences between them.
  • The same can be said about other frameworks such as Pyramid or TurboGears2. To determine which framework is right for you (and why), head over to Stack Overflow, where users frequently discuss topics related to open-source web development tools and languages like Python.

What are the key features of Python?

  • Python's key features include its syntax, interpreter, dynamic nature, broad standard library, and a collection of third-party modules available for Python.
  • The language also supports multiple programming paradigms, including object-oriented, imperative and functional programming or procedural styles.
  • It was designed to emphasize code readability and a syntax that allows programmers to express concepts in fewer lines of code than would be possible in languages such as C++ or Java. The language has a large and comprehensive standard library.

What are Keywords in Python?

  • Keywords are reserved words in Python. These words have a specific meaning to Python, so they can't be used as user-defined or variable names.
  • Some of these keywords may change with new versions of Python; most are used to control syntax and grammar, although some (e.g., True and False) do have values that can assign to variables.

What are functions in Python?

Python functions are like other programming languages, such as C and Java. A function is a block of code that performs a specific task. When you call a function from another block of code, it carries out that task and returns a value to its caller. For example, here's how you might write a very simple factorial program in Python: def fact(n): Compute n!; n>=0 if n == 0: return 1 else: return n * fact(n-1)

How to Install Python?

Installing Python on your system is extremely easy. Go to Python's website and follow the instructions. The entire process can be completed in a matter of minutes, depending on your Internet connection speed.

What is Python Used?

  • Python is used in various applications such as Desktop GUIs, Administration tools, and Web Development.
  • It is also used in scientific research and is even taught to high school students in many countries.
  • Guido van Rossum created the language while at CWI, Dutch Research Institute for Mathematics and Computer Science.
  • He released it to be open-source software on February 2nd, 1991. means that anyone can freely use Python for any purpose.

What is Pandas?

  • Pandas is a python library that has data structures and data analysis functions. Pandas provide high-performance, easy-to-use data structures that make working with relational or labelled data easy and intuitive.
  • It aims to facilitate workflows requiring access to heterogeneous data types and multiple data types. Pandas is built on top of NumPy and distributed as part of SciPy.

What are data frames?

  • In Python, a dataframe is an ordered collection of columns of data. Think of it as being similar to a spreadsheet or SQL table.
  • Dataframes are used for the storage and manipulation of datasets in Python.
  • Most machine learning algorithms require you to import your dataset into a dataframe before running them.
  • Thus, it is important to know how to work with data frames when doing machine learning in Python. For example, let's look at our favourite dataset: Titanic Passengers.

What kind of joins do pandas offer?

Pandas only offer inner joins and left outer joins at present. They are equivalent to SQL's INNER JOIN, LEFT OUTER JOIN, and FULL OUTER JOIN.

What are comments, and how can you add comments in Python?

When Python parses your program, it ignores lines of code that start with a hash (or pound) sign. When you want to include one of these special lines in your program but don't want Python to execute it, you can use it as a comment and mark it with a pound sign at the beginning. Comments are used to provide information about what's happening or why things are done in a certain way.o
There are two types of comments which include:

  1. Single-line comment
  2. Multiple-line comment
    Codes needed for adding a comment

Note – Single line comment

""" This is
Comment """—–multiline comment

What is the difference between lists and tuples in Python?

  • A list is an ordered collection of objects (similar to an array in other languages). Tuples are immutable lists.
  • There are some minor syntactical differences: a trailing comma may be present in tuples but not lists, and a tuple item can be assigned by position or keyword while it must be posted by keyword in the case of a list. Otherwise, they have very similar semantics.
  • The main conceptual difference between tuples and lists is that tuples represent a fixed number of values, whereas lists allow any number of values to be added.
  • Additionally, tuples do not support element deletion or slicing (but slices from ranges generally work as expected), whereas both operations work for lists as desired. Finally, len() works on tuples just like for strings; its result, however, corresponds to the number of items rather than length in bytes as for strings.

What is a dictionary in Python?

The Python dictionary is a collection of key:value pairs, where both keys and values are arbitrary objects. There are several ways to create a dictionary in Python.

What is a classifier?

  • A classifier is a function that can categorize something into one of a given number of categories.
  • Classifiers are trained and become better with experience, similar to training an animal. They can be as simple as an if statement or as complex as a neural network.
  • The most common use case for classifiers is data mining, where large amounts of unstructured data (images, text, etc.) must be automatically categorized or classified.

What is recursion?

Recursion is a programming technique where a function or procedure calls itself (or other instances) during its operation. If you're trying to understand recursion for interviews, chances are you'll be asked about recursive functions in Python. Here are some tips

Explain Python List Comprehension

  • List comprehension is used to construct lists.
  • List comprehensions are similar to set and dictionary comprehensions, but they return lists instead of sets or dictionaries.
  • The syntax for a list comprehension consists of brackets containing an expression followed by a for clause, then zero or more for or if clauses.
  • A trailing else clause can be added after all for and if-clauses. Here's an example that returns the squares of numbers from 1 to 10: [x**2 for x in range(1, 11)]

What is the 'with the statement'?

A with statement is a Python statement that binds its body to a particular name. Within a block, you can also access attributes of an object's dict. As with Python's standard globals() module, if you attempt to access or assign a point of a bound object within a block and that object does not define it, an AttributeError will be raised.

What is init in Python?

It is a special method that should be present in each class. This method will be invoked when an instance of a class is created. The init method takes no parameters and has to return self (which, in Python, means it has to return an instance of itself).

What is pass in Python?

Unlike many other languages, in Python, you don't specify a return type for functions or methods. Instead, the return value is determined by what you do in your function or method.

What are modules and packages in Python?

  • Python is a programming language, which means that it is designed to write computer programs.
  • These programs are written using a set of instructions called a programming language. Python is one such programming language. T
  • o solve complex problems in Python, you need a few building blocks called modules and packages.

What is the object() function in Python?

This is a very simple Python Interview question to test your knowledge. Object() function helps to create objects in Python. All things are created by object() function. It returns a reference of an object or None if no argument is passed to it. Here's an example for better understanding

What is the difference between NumPy and SciPy?

NumPy and SciPy are Python libraries that can run code related to mathematics, science, and engineering. NumPy is a library for numerical computation that adds support for multidimensional arrays and matrices to Python.

SciPy is a library of algorithms for mathematics, science, and engineering that builds on top of NumPy. Many people use both in combination because they are designed to work together.

Define Encapsulation in Python?

Encapsulation means data members (variables) and functions (code blocks) can be hidden in classes. In addition, only objects of a class can access its internal data members and parts.

What is the type () in Python?

Python is a dynamically typed programming language. This means that you don't have to declare a variable before using it. In Python, if you want to refer to a variable called x, and you haven't said it yet, then start typing x. The interpreter will figure out that you mean x and create it before executing your code.

What is the split() function used for?

  • This function takes an expression or a sequence of expressions and returns a list of lists, with each inner list containing one item from the input sequence.
  • So let's say we have a string s = ABC and we call split(s) it will return [['a'], ['be], ['c']] . If all elements are not the same, you will get None as output.

What is docstring in Python?

  • A docstring is a string that appears as the first statement in a Python module, function or class. It should give an overview of what the code does and, if needed, reference external documentation for more details.
  • IDEs often use docstrings to provide contextual information about what is happening in your program. A good docstring can help make your code more easily understood by other programmers who read it, even if they haven't seen it before.

How to Reverse a String in Python?

Strings in Python can be reversed using List Comprehension. The syntax is as follows, s = for char in reversed(string): s += char print(s). This will reverse a string, word by word.

What are the different functions that groups in pandas can use?

An easy solution to load a local CSV file into a DataFrame in pandas . import pandas as pd df = pd.read_csv('myfile.csv') gdf = grouby(df) print gdf.sample(False, 5)

How do we interpret Python?

  • Python is an interpreted high-level programming language for general-purpose programming.
  • Its design philosophy emphasizes code readability, and its syntax allows programmers to express concepts in fewer lines of code than would be possible in languages such as C++ or Java.
  • The language provides constructs intended to enable clear programs on both a small and large scale. - How do we interpret Python?

Explain the file processing modes that Python supports.

  • Python supports two modes for reading a file, sequential and random access. Sequentially, you read data from a file character by character until you reach an end-of-file marker or reach a specific line number.
  • Line numbers are indicated with parentheses after each expression. In random access mode, you can use Python's built-in variables f.tell() and to position your cursor at a specific line of text in a file;

How is memory managed in Python?

  • In Python, all memory management is done automatically.
  • There is no explicit new and delete statements to allocate and free memory.
  • When you create an object using a class, Python allocates enough space from the heap to hold it and any data members it may have (variables defined in its enclosing scope).
  • As more objects are created, larger memory segments get allocated from the heap.

What are Python decorators?

  • A decorator is a function that takes another function as an argument and returns a modified version of that function.
  • It's useful for adding behaviour to an existing function without changing it directly.
  • They are so named because they decorate their input functions with different behaviour, like decoration on a Christmas tree.
  • You can use any callable Python object (like a class or even another decorator) as a decorator.

What do you understand by object-oriented programming in Python?

  • There are two ways to do OOP in Python: extending existing classes or defining new ones. The most important part of object-oriented programming is Encapsulation.
  • There will be a lot of focus on how you will implement it in your code.
  • A simple example would be, How can you ensure that no one else can directly access your methods? This would require you to use some sort of wrapper or abstraction.

What is inheritance in Object-oriented programming?

  • Inheritance is one of several object-oriented programming (OOP) concepts that allows objects to be defined in terms of other, already existing things.
  • The goal of inheritance is to make it easy for developers to reuse code, thus making software development more efficient.
  • This is accomplished by creating new classes similar in purpose or functionality to existing courses and then extending those classes using inheritance.

What is multi-level inheritance?

  • Multiple inheritances is a form of inheritance in which an object or class can inherit attributes and methods from more than one parent class.
  • The concept of various inheritances was introduced to accommodate bidirectional relationships (such as those between parents and children) and mutual exclusion of implementations, neither supported by single inheritance.

When will I get a response from my interview application? How do I prepare for an interview in Python? What should I wear to a Python Interview? What are some good questions to ask at a Python Interview? When should I follow up after an interview in Python?

How do you stand out in a Python coding interview?

If you're a Python coder looking for your next gig, then you'll know how competitive it is out there. To increase your chances of getting that coveted job offer, we've compiled a list of questions that you might be asked during a Python interview. Read through them and make sure you can tackle these questions confidently—you never know when they could crop up in an interview!

How do I prepare for a Python interview?

If you're appearing for a technical round of interviews for Python, make sure you're well prepared. Ask your recruiter or contact Google or Facebook to share a copy of their coding test/interview questions beforehand. Google publishes it here, and so does Facebook, as do many other big tech companies.

Are our Python coding interviews very difficult?

The term interview is so overused that people sometimes forget what it means. An interview tests your ability to apply your knowledge in a simulated real-world scenario (in other words, in a practical context). In other words, an interview doesn't test how well you know Python syntax or how familiar you are with different design patterns. Instead, it tests your ability to think and act like a professional programmer—which isn't something many developers think about very often.

How do I pass the Python coding interview?

When you're applying for a job as a Python developer, you may find yourself facing an interview that includes a coding exercise. While they might be nerve-wracking, you can prepare by developing your coding problem and figuring out how to solve it.

Which courses or certifications can help boost knowledge in Python?

If you want to take up Python certification, your first stop should be edX. This platform offers two courses on Python and several related studies in machine learning and data science. The website boasts of more than 50 million learners who have signed up for its various online training programs that are offered free of cost.

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