Top Python Interview Questions and Answers

Since Python continues to be the fastest-growing programming language out there today, the number of career opportunities where knowledge of the language is important is increasing correspondingly. As a result, any candidate who wants to ace that crucial programming interview should have knowledge of Python as part of their skillset.

Additionally, Python is a good choice for current data analysts and data scientists who want to improve and upskill their knowledge base, since the language is widely used in those fields. It stands to reason that anyone who wants to increase their value in an analytics/data science position should learn and understand Python’s fundamentals.

But for now, let’s focus on those of you who are going on that all-important Python-related interview. The funny thing about interviews is that it’s easy to get nervous and flustered, resulting in you forgetting information that you would otherwise routinely know. It’s the pressure, you see; sometimes it gets to you. That could spell big trouble if the interview veers into technical details.

That’s why it’s important to have a means of refreshing your memory, a way of preparing yourself for those inevitable technical questions. That’s why you need this article!

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The following is a series of the most common Python-related interview questions and answers. Check them out, brush up on your knowledge, and tackle that interview with increased confidence!

We’ll start with the super-easy questions, and work our way up to the more challenging ones.

Question 1: What is Python?

Python is a high-level, interactive, interpreted, and object-oriented programming language.

Question 2: What are the benefits of Python?

In comparison to other languages, Python uses English keywords and has fewer syntactical constructions. This makes Python highly readable and a very easy language to learn. On top of this, it is also an open source language programming language.

Question 3: Speaking of benefits, spell out some of Python’s more noteworthy features.

Among Pythons more useful features: Python supports automatic garbage collection

  • It can be easily integrated with C, C++, COM, ActiveX, CORBA, and Java
  • Python can be used as either a scripting language or be compiled to bytecode for the building of large applications
  • It supports functional and structured programming methods as well as Object-Oriented Programming (OOP).

Question 4: What is PEP 8?

PEP 8 is a set of recommendations for how to write your Python code in a more readable format. It’s is a coding convention.

Question 5: What’s pickling and unpickling?

Pickling is the process of converting a Python object hierarchy into byte stream. Unpicking is just the opposite - converting a byte stream back to an object hierarchy. Other alternate terms used for these processes are “serialization”, “marshalling,” and “flattening”.

Question 6: What is the purpose of PYTHONPATH environment variable?

The variable has a role similar to PATH. It tells the Python interpreter where to locate the module files that are imported into a program, and this information should include the Python source library directory as well as the directories containing Python source code. Additionally, PYTHONPATH is occasionally preset by the Python installer.

Question 7: What are Python decorators?

The decorator is a specific change made in Python syntax to easily alter functions. And no, they have nothing to do with people who dress up snakes in colorful fashions or give them tattoos.

Question 8: What is PEP 8?

Pep 8 is a set of recommendations and coding conventions designed to show you how to make your Python coding more readable.

Question 9: Is Python is a case-sensitive language?

Yes, it is.

Question 10: How is memory managed in Python?

Python uses a private heap space for memory management. Therefore, all the objects and data structures will be located in a private heap, although the programmer is not given access to this heap. Rather, the Python interpreter handles the private heap. Concurrently, the core API enables the programmer to have access to some Python tools in order to start coding.

The memory manager allocates the heap space for the Python objects while the inbuilt garbage collector recycles all of the memory that’s not being otherwise employed in boosting available heap space.

Question 11: How do you delete a file in Python?

Use either os.remove (filename) or os.unlink(filename)

Question 12: What is namespace in the context of Python?

In Python, "name" is simply a name given to Python objects. Namespace maps every "name" that you define to the corresponding objects. It is analogous to a box which contains all the built-in names. Whenever the programmer searches out the variable, this box is searched in order to get the corresponding object.

Question 13: What is Flask, and what is it good for?

Flask is a third-party Python library used to develop web applications for Python. It started as a wrapper around Werkzeug and Jinja, and has grown in popularity. It is also considered a light framework because it barely has any dependencies on external libraries.It is ideal for building smaller applications, unlike Pyramid, which is designed for larger applications. Flask’s simplicity also means there is little dependency to update and less security bugs.

Question 14: What is the dogpile effect, and how can it be prevented?

The dogpile effect is what you get when the cache expires, while at the same time, websites get hit by multiple client requests. The dogpile effect can be prevented by employing a semaphore lock. In this system, when the value expires, the first process acquires the lock and then generates a new value.

Question 15: How do you make a Python script run on Unix?

Take the following two steps:

  • Script file's mode must be executable
  • The first line must begin with # ( #!/usr/local/bin/python)

Question 16: Name the five data types supported by Python, and which ones are mutable and which are immutable?

The types are:

  • Numbers
  • String
  • List
  • Tuple
  • Dictionary

Lists, dictionaries, and sets are all mutable, which means that you can change their content inside them while keeping their identity the same.. Strings and tuples are immutable, so their contents can’t be changed once they’re created.

Question 17: What tools are used to help find bugs and perform static analyses?

PyChecker and Pylint are the two main tools.. Pychecker is a static analysis tool checks the Python script for bugs and alerts the programmer regarding the style and complexity of the bug. Pylint verifies whether the module meets the coding standard.

Question 18: What is the PYTHONPATH environment variable’s purpose?

PYTHONPATH has a role much like PATH. This particular variable lets the Python interpreter know where to locate the module files which are imported into a program. This should include the Python source library directory as well as the directories containing Python source code. PYTHONPATH is often times preset by Python’s installer.

Question 19: How about the purposes of PYTHONSTARTUP, PYTHONCASEOK, and PYTHONHOME?

PYTHONSTARTUP contains the path of an initialization file that contains Python source code. It’s executed every time you start the interpreter. It’s named in Unix and contains commands that load utilities or modify PYTHONPATH.

PYTHONCASEOK is used in Windows for finding modules on file systems which are case-sensitive. It is activated by setting the variable to any value.

PYTHONHOME is an alternative module search path, usually embedded in the PYTHONSTARTUP or PYTHONPATH directories in order to make switching module libraries easy.

Question 20: Explain the difference between lists and tuples.

List objects are contained in brackets [ ] and they can be changed. Tuple objects are contained in parentheses ( ) and they cannot be changed.It helps if you consider Tuples as read-only lists.

Question 21: In the context of Python, what is a module?

A module in python helps to organize your Python code in a logical way. It contains import statements, functions, classes and variable definitions, plus Python runnable code. Each Python program file is actually a module, which in turn imports other modules such as objects and attributes.

Question 22: What’s a dictionary?

A Dictionary in Python is similar to the Dictionary in a real world and works like associative arrays or hashes found in Perl. It contains key-value pairs which are used to store data values. Although almost any Python type can be a dictionary key, they are usually numbers or strings.

Question 23: So how do you make a dictionary?

Dictionaries can be created by using curly braces {}. The values for the dictionary can be assigned and accessed using square braces [].

dict = {}

dict['one'] = "This is one"

dict[2]     = "This is two"

tinydict = {'name': 'john','code':6734, 'dept': 'sales'}

Question 24: One of these is an invalid statement. Which one?

  1. abc = 1,000,000
  2. a b c = 1000 2000 3000
  3. a,b,c = 1000, 2000, 3000
  4. a_b_c = 1,000,000

The correct answer is “b”.

Question 25: Write a sorting algorithm for a numerical dataset in Python.

This code can be used to sort a list in Python:

list = [“1”, “4”, “0”, “6”, “9”]

list = [int(i) for i in list]


print (list)

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Do You Want to Learn More About Python?

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About the Author

John TerraJohn Terra

John Terra lives in Nashua, New Hampshire and has been writing freelance since 1986. Besides his volume of work in the gaming industry, he has written articles for Inc.Magazine and Computer Shopper, as well as software reviews for ZDNet. More recently, he has done extensive work as a professional blogger. His hobbies include running, gaming, and consuming craft beers. His refrigerator is Wi-Fi compliant.

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