Interview questions on Python

Python Data Science Interview Questions 

If you’re looking to build a career in data science, you already know how important Python will be. The significance of Python data science interview questions at interviews has risen exponentially. After all, it is the most widely used language in data science.

Q1. What is Python?

-    High level, interpreted & object-oriented scripting language.

-    Readable code and large library.

-    Works on all operating systems.

Q2. What are the Features of Python?

-    It's open source language.

-    It's an interpreted language that means easy to debug.

-    Supports both procedure and object-oriented programming.

-    Portable that means which can run on different platforms.

Q3. Can you explain how is python interpreted?

-    Source Code --> Intermediate language --> Native Language--> Execution

Q4. How's memory management in Python?

-    Memory management in python involves a private heap containing all Python objects and data                     structures.

-    It's ensured by the Python memory manager.

-    Built in garbage collector recycles all unused memory.

Q5. What is a Python Dictionary?

-    Like a real-world dictionary.

-    Stores the data as key-value pairs.

-    All the keys in dictionary have to be unique.

-    Key separated from it values by colon (:)

-    Key, value pairs separated by comma (,)

Q6. What are the tuples?

-    Tuple is a immutable that means once created cannot change.

-    Used to store read-only operations.

-    Denoted by parenthesis "( )".

Q7. What are the lists?

-    Lists are mutable that means once created we can change.

-    Denoted by Square Brackets "{ }"

Q8. Explain the operators - // , % , ** in python?

-    //   : Floor Division

            1. Result- Quotient with decimal values removed.

            Example: if a=5,b=2 then a//b=2

-    % : Modulus

            1. Result- Gives the reminder 

-    ** : Exponent

            1. It performs the calculation on operands that means 'power'.

Q9. What is Python, and what is it used for?

An interpreted high-level, general-purpose programming language, Python is often used in building websites and software applications. Apart from this, it is also useful in automating tasks and conducting data analysis. While the programming language can create an array of programs, it hasn’t been designed keeping in mind a specific problem(s). 

Q10. List the important features of Python.

Some significant features of Python are:

• It supports structured and functional programmings
• It developed high-level dynamic data types
• It can be compiled to byte-code for creating larger applications
• It uses automated garbage collection
• It can be used along with Java, COBRA, C, C++, ActiveX, and COM

Q11. What are the different built-in data types in Python?

Python uses many built-in data types. Some of these are:

• Number (int, float, and complex)
• String (str)
• Tuple (tuple)
• Range (range)
• List (list)

Q12. Explain how Python data analysis libraries are used and list some common ones.

The collection of data analysis libraries used in Python includes a host of functions, tools, and methods that manage and analyze data. Some of the most popular Python data analysis libraries are:

• NumPy
• SciPy
• TensorFlow
• SciKit
• Seaborn

Q13. What is a negative index used for in Python?

Negative indexes in Python are used to assess and index lists and arrays from the end, counting backward. For instance, n-1 shows the last time in a list while n-2 shows the second to last. 

To understand such technical concepts better, go over our Learn section. We have covered several topics in great detail to help you prepare Python data science interview questions. 

Q14. What does it mean when we say that Python is an object-oriented language?

When we say Python is an object-oriented language, we mean that it can enclose codes within the objects. When the property permits the storage of the data and the method in a single unit, it is known as the object. 

Q15. Explain a Python module. What makes it different from libraries? 

A single file or many files containing functions, definitions, and variables created to perform certain tasks is called a module. It’s a .py extension file that can be imported at any given point and needs to be imported just once. 

A library is a collection of reusable functionality of code that’ll allow users to carry out a number of tasks without having to write the code. A Python library doesn’t have any specific use but refers to a collection of modules. 

This question is one of the most popular Python data science interview questions.

Q16. What is PEP8?

Coding convection PEP8 contains coding guidelines. These are a set of recommendations put together for the Python language that make the language more readable and easy to use for users.

Q17. Name some mutable and immutable objects. 

The ability of a data structure to change the portion of the data structure without needing to recreate it is called mutability. These objects include lists, sets, values in a dictionary.

Immutability is the state of the data structure that can’t be tampered with after its creation. These objects are integers, strings, and keys of a dictionary. 

Q18. What are generators and decorators?

The generator function is responsible for simplifying the process of creating an iterator. A decorator manipulates pre-existing functions or their output, which it does by adding, deleting, or altering characteristics.   

Q19. Differentiate between %, /, and //?

% (Modulus operator) is responsible for returning a remainder after the division.

/ (Operator) it returns the quotient post division.

// (Floor division) it rounds off the quotient to the bottom.

Q20. What is the lambda function?

• These are anonymous or nameless functions.
• Lambda functions are anonymous as they aren’t declared in the standard manner using the def keyword. Further, it doesn’t even need the return keyword. Both are implicit in the function.
• These functions have their local namespace and don’t have any access to variables other than those in their perimeter list and those in the global namespace. 
• Examples: x = lambda i,j: i+j

print (x(7,8))

Output: 15

Yet another important question in this list of Python data science interview questions. So prepare accordingly. 

Q21. Explain the map, reduce and filter functions.

Q22. What is the difference between range, xrange, and arange?

• range() - Returns a Python list object (a sequence of integers). It’s a BASE Python function.
• xrange() - Returns a range object.
• arange() - It’s a function in the Numpy library and can also return fractional values.

Q23. How do you differentiate between global and local variables?

Variables that are defined and declared outside a function and need to be used inside a function are called global variables. When a variable is declared inside the function’s body, it is called a local variable. 

Q24. What is the difference between pass, continue and break?

Pass: It is used when you need some block of code syntactically, but you want to skip its execution. This is basically a null operation. Nothing happens when this is executed.

Continue: It allows to skip some part of a loop when some specific condition is met, and the control is transferred to the beginning of the loop. The loop does not terminate but continues with the next iteration.

Break: It allows the loop to terminate when some condition is met, and the control of the program flows to the  statement immediately after the body of the loop. If the break statement is inside a nested loop (the loop inside another loop), then the break statement will terminate the innermost loop.

Q25. What is the difference between del(), clear(), remove(),  and pop()?

• del(): deletes the with respect to the position of the value. It does not return which value is deleted. It also changes the index towards the right by decreasing one value. It can also be used to delete the entire data structure.

• clear(): clears the list.

• remove(): it deletes with respect to the value hence can be used if you know which particular value to delete.

• pop(): by default removes the last element and also returns back which value is deleted. It is used extensively when we would want to create referencing. In sense, we can store this deleted return value in a variable and use in future. 

Q26. What are the local variables and global variables in python?

In Python, there are two types of variables local variable and global variable.

Local Variable:

If the variable is declared inside the body of method or function then that variable is accessible inside that method/function only. This variable is known as Local Variable.

For an example:

def func():
    x = "local variable"
    print(x)
func()

Global Variable:

If the variable is declared in global scope or outside the method, is known as a global variable. Global variable can be accessed from anywhere inside the projects.

For example:

x = "global variable"
def func():         
    print(x)
func()