Python programming language ranks third among the most loved languages by developers worldwide, finds this year’s Stack Overflow Survey. In addition, developers who don’t know Python say that it is the top language they want to learn. Its popularity is increasing especially among data scientists, machine learning engineers and artificial intelligence professionals. Several jobs in these fields require applicants to be proficient in the language. If you are an aspiring data scientist, learn Python. Here are some Python interview questions you are likely to encounter and some suggestions for answering them.

Top 16 Python Interview Questions & Answers

Python interviews are likely to be more of a test than an interview. While the theory is something you need to be strong at, be prepared to answer practical questions and write code during the interview. In this blog post, we’ll see some of the most commonly asked Python technical interview questions.

#1 Why is coding in Python good for data science or machine learning applications?

Python programming language is open source, making it both free and supported by a large global community. Compared to other languages like Java or C++, Python’s syntax is simpler, code is readable and easy to learn. It has a great ecosystem of frameworks and libraries including TensorFlow, Pandas, Keras, Scikit-learn and so on. It is platform-independent and combines well with other languages. It also supports automatic garbage collection and is very user-friendly to do visualisations.

#2 Python Interview Questions: How is memory handled in Python?

The Python memory manager allocates memory in the form of private heaps for objects and data structures. It also manages functions like storing, caching, segmentation, etc.

#3 What is PEP8? What are some recommendations in PEP8?

PEP is Python Enhancement Proposal. It’s a set of guidelines for programming with Python. Its core goal is to make Python code more readable. It includes suggestions for naming conventions, code layout, indentation, comments, etc. It also recommends the best function to use for a specific purpose. You can read the whole PEP8 documentation here.

#4 What is a list? What is a tuple? How are they different?

List and tuple are both sequence data types. Lists are mutable, i.e. they can be edited. But tuples are immutable, once created, they can’t be altered. Also, lists are typically used for ordered sequences of the same type of object. Tuples can have different data types in each index.

#5 In Python, what’s the difference between “is” and “==”?

‘Is’ checks for identity. ‘==’ checks for equality. For instance, two variables may be equal, but they are not the same. If x = 1 and y = 1, print(x == y) will return true, but print(x is y) will return false.

#6 Python Interview Questions: What is the range function?

Range generates a list of integers. range(stop) gives a range from 0 to stop integer. range(start, stop) gives a range from start integer to stop integer. range(start, stop, step) returns integers from start to stop at ‘step’ intervals.

#7 What is the difference between “func” and “func()”?

In Python, all functions are also objects. ‘func’ is the object representing the function. ‘func()’ calls the function and returns the output.

#8 Is there a difference between lower case, upper case and title case in Python?

Yes, Python programming language is case sensitive.

#9 Can you show a few ways to display a string literal?

You can display a string literal using the print() function, with single or double quotes.

Simple print string
print(‘Springboard’)
Output: Springboard
Slicing
x = “Springboard”
print(x[2:6])
Output: ring
String length
x = “Springboard”
print(len(x))
Output: 11
Change case
x = “SPRINGBOARD”
print(x.lower())
Output: springboard
Concatenate
x = “Spring”
y = “board”
z = x + yprint(z)
Output: Springboard

#10 Python Interview Questions: What are Python dictionaries?

Dictionary is another data type in Python. It is key: value pairs, where the keys are unique. They are written in curly brackets. For example, we can create and print a dictionary like below.

StudentProfile = {

  “Name”: “Jane Doe”,

  “Age”: “32”,

  “Career”: “Data scientist”

}

print(StudentProfile)

Output will be: {‘Age’: ’32’, ‘Name’: ‘Jane Doe’, ‘Career’: ‘Data scientist’}

#11 What is the difference between dictionaries and JSON?

Like we said above, dictionaries are data types within Python. JSON is a string in a predetermined format for transferring data.

#12 Which is faster for lookups: List or dictionary?

Dictionaries are faster for lookups because they are hash tables. If there is only one key, and not a key: value pair, a set would also do the job fast.

#13 Python Interview Questions: How are bugs found on Python?

Typically, Python programmers use two tools to find bugs. PyChecker to detect the bugs in source code. Pylint to check if the module meets the coding standard.

#14 How to remove duplicates from a list?

This is something data analysts and data scientists do a lot during the cleaning process. In Python, it can be done by converting a list to a set and then back to a list.

x = [1,2,3,3,2]

x = list(set(x))

print(x)

Output: [1, 2, 3]

#15 What is the difference between append and extend?

Append can add only one value to any list. Extend can add a list to a list.

x = [1,2,3]
x.append(4)
print(x)

Output: [1, 2, 3, 4]
x = [1,2,3]
x.extend([4,5,6])
print(x)

Output: [1, 2, 3, 4, 5, 6]

#16 Python Interview Questions: Why do you like Python?

This is, of course, a personal question. There is no ‘best way’ to answer this. Just be authentic to yourself. If you like it because it’s easy, say so. If you don’t like it, feel free to say that too. And explain the reasons behind your feelings. It will help them understand what your priorities and discomforts are.

This is a good bunch of questions to start with. However, you might get a lot more practical Python coding interview questions, for which you will need to know to code on the spot. So, be prepared for the most common functions used in Python. It will also help if you have a portfolio of projects built in Python to demonstrate your practical skills. If you’re looking to learn Python for machine learning or data science applications, consider Springboard’s online learning programs. In addition to 1:1 mentorship from industry leading professionals, career coaching, and hands-on projects, it also offers a job guarantee.