Python Interview Questions and Answers

Ques 1. What are the differences between Python 2 and Python 3?

Please refer Python 2 vs Python 3.

Ques 2. How can we access a module written in Python from C?

We can access the module written in Python from C by using the following method.

Module == PyImport_ImportModule("<modulename>");

Ques 3. How do you copy an object in Python?

To copy objects in Python we can use methods called copy.copy() or copy.deepcopy().

Example:

fruits = ["apple", "banana", "cherry"]

x = fruits.copy()

print(x)

Output:

Ques 4. What is the procedure to install Python on Windows and set path variables?

We need to implement the following steps to install Python on Windows, and they are:

• First, you need to install Python from https://www.python.org/downloads/
• After installing Python on your PC, find the place where it is located in your PC using the cmd python command.
• Then visit advanced system settings on your PC and add a new variable. Name the new variable as PYTHON_NAME then copy the path and paste it.
• Search for the path variable and select one of the values for it and click on ‘edit’.
• Finally, we need to add a semicolon at the end of the value, and if the semicolon is not present then type %PYTHON_NAME%.

Ques 5. Differentiate between SciPy and NumPy?

The difference between SciPy and NumPy is as follows:

Ques 6. What is Django? What are different interview questions and answers on Django?

Please refer Django interview questions and answers.

Ques 7. List the ways we add view functions to urls.py.

• Adding a function view
• Adding a class-based view

Ques 8. What is flask and provide some interview questions and answers?

Please refer Flask interview questions and answers.

Ques 9. What is the Dogpile effect?

This is defined as an occurrence of an event when the cache expires and also when the websites are hit with more requests by the client at a time. This dogpile effect can be averted by the use of a semaphore lock. If in the particular system the value expires then, first of all, the particular process receives the lock and begins generating new value.

Ques 10. Does Python replace Java?

Python alone can't replace Java, whereas a group of programming languages can replace Java but JVM can't be replaced.

Ques 11. How to crack a coding interview?

It is not that easy as we usually think. Mugging up some programs and executing the same will not work. The ideal way to crack the coding interview, you should be proficient in writing code without the support of any IDE. Don't panic or argue, test your code before you submit, wait for their feedback. Practicing mock interviews will help.

Ques 12. Top 5 tips to crack the python interview?

The following are the top 5 tips to crack Python interview:

• Building a proper profile will fetch you better results
• Setting up your portfolio might impress your interviewer
• Learn all the fundamentals of Python and OOps concepts as 90% of the interview start from basics
• Feel free to write code pen and paper
• Apart from all the above practice is what required.

Ques 13. What is nested function in Python?

In Python, we can create a function inside another function. This is known as a nested function. For example,

def greet(name):
    # inner function
    def display_name():
        print("Hi", name)
    
    # call inner function
    display_name()

# call outer function
greet("John")  

Output:

Hi John

In the above example, we have defined the display_name() function inside the greet() function.

Here, display_name() is a nested function. The nested function works similar to the normal function. It executes when display_name() is called inside the function greet().

Ques 14. What is Python Closures?

As we have already discussed, closure is a nested function that helps us access the outer function's variables even after the outer function is closed. For example,

def greet():
    # variable defined outside the inner function
    name = "John"
    
    # return a nested anonymous function
    return lambda: "Hi " + name

# call the outer function
message = greet()

# call the inner function
print(message())

Output:

Hi John

In the above example, we have created a function named greet() that returns a nested anonymous function.

Ques 15. When to use closures? So what are closures good for?

Closures can be used to avoid global values and provide data hiding, and can be an elegant solution for simple cases with one or few methods.

However, for larger cases with multiple attributes and methods, a class implementation may be more appropriate.

Ques 16. What is the difference between append() and extend() methods?

Both append() and extend() methods are methods used to add elements at the end of a list.

• append(element): Adds the given element at the end of the list that called this append() method
• extend(another-list): Adds the elements of another list at the end of the list that called this extend() method

Ques 17. How is Multithreading achieved in Python?

Python has a multi-threading package ,but commonly not considered as good practice to use it as it will result in increased code execution time.

• Python has a constructor called the Global Interpreter Lock (GIL). The GIL ensures that only one of your ‘threads’ can execute at one time.The process makes sure that a thread acquires the GIL, does a little work, then passes the GIL onto the next thread.
• This happens at a very Quick instance of time and that’s why to the human eye it seems like your threads are executing parallely, but in reality they are executing one by one by just taking turns using the same CPU core.

Ques 18. What is functional programming? Does Python follow a functional programming style? If yes, list a few methods to implement functionally oriented programming in Python.

Functional programming is a coding style where the main source of logic in a program comes from functions.

Incorporating functional programming in our codes means writing pure functions.

Pure functions are functions that cause little or no changes outside the scope of the function. These changes are referred to as side effects. To reduce side effects, pure functions are used, which makes the code easy-to-follow, test, or debug.

Python does follow a functional programming style.

Ques 19. What is monkey patching in Python?

Monkey patching is the term used to denote the modifications that are done to a class or a module during the runtime. This can only be done as Python supports changes in the behavior of the program while being executed.

Ques 20. What is pandas?

Pandas is an open source python library which supports data structures for data based operations associated with data analyzing and data Manipulation. Pandas with its rich sets of features fits in every role of data operation,whether it be related to implementing different algorithms or for solving complex business problems. Pandas helps to deal with a number of files in performing certain operations on the data stored by files.

Ques 21. What are dataframes?

A dataframe refers to a two dimensional mutable data structure or data aligned in the tabular form with labeled axes(rows and column).

• data:It refers to various forms like ndarray, series, map, lists, dict, constants and can take other DataFrame as Input.
• index:This argument is optional as the index for row labels will be automatically taken care of by pandas library.
• columns:This argument is optional as the index for column labels will be automatically taken care of by pandas library.
• Dtype: refers to the data type of each column.

Ques 22. What is regression?

Regression is termed as supervised machine learning algorithm technique which is used to find the correlation between variables and help to predict the dependent variable(y) based upon the independent variable (x). It is mainly used for prediction, time series modeling, forecasting, and determining the causal-effect relationship between variables.

Scikit library is used in python to implement the regression and all machine learning algorithms.

There are two different types of regression algorithms in machine learning :

Linear Regression: Used when the variables are continuous and numeric in nature.

Logistic Regression: Used when the variables are continuous and categorical in nature.

Ques 23. What is classification?

Classification refers to a predictive modeling process where a class label is predicted for a given example of input data. It helps categorize the provided input into a label that other observations with similar features have. For example, it can be used for classifying a mail whether it is spam or not, or for checking whether users will churn or not based on their behavior.

These are some of the classification algorithms used in Machine Learning:

• Decision tree
• Random forest classifier
• Support vector machine

Ques 24. What is SVM?

Support vector machine (SVM) is a supervised machine learning model that considers the classification algorithms for two-group classification problems. Support vector machine is a representation of the training data as points in space are separated into categories with the help of a clear gap that should be as wide as possible.