Top 80 Python Interview Questions & Answers

18-Aug-2022

One of the most used programming languages nowadays is Python. This object-oriented language is used by significant corporations throughout the globe to create programs and applications. You will find some of the most frequently asked questions about Python in various fields in this article. You can prepare for interviews using this list of top Python interview questions and answers for experienced and new developers. Here are some of the most well-known and important Python interview questions and answers:

Basic level Python Interview Questions and Answers

1. Define Python.

Python is a powerful programming language that is interactive, interpreted, and object-oriented. It commonly makes use of English keywords. Python has fewer syntactic constructions in comparison to other languages that use punctuation.

Python is made to be very legible and works on a variety of operating systems, including Mac, Linux, Windows, Raspberry Pi, etc. 

2. How is Python an interpreted language?

Any programming language that runs its statements line by line is said to be an interpreted language. Python programs do not require a compilation phase before running because they can be run directly from the source code. 

3. Differentiate List from Tuples

Let us classify the difference between Tuples and List in the following points:

List is changeable while Tuples are not and they cannot be edited.

Tuples are faster in comparison to lists as the list takes longer. 

The list requires a lot of memory while tuples don't.

Lists are less error-proof because unforeseen changes are more likely to happen. However, tuples are more dependable because it is more difficult for any unexpected change to occur.

Tuples don't have any built-in features. While Lists come with many built-in functions. 

4. Describe Pep 8.

Python Enhancement Proposal is known as PEP. It is a collection of guidelines for creating code in Python that is as readable as possible.

5. What are Python's main characteristics?

Let us point out the main characteristics of Python in the following points:

• In contrast to other languages like C, Python is an interpreted language, which implies it does not require compilation before execution. 
• There is no need to declare a variable with the data type because Python is dynamically typed. The value of the variable will be used by the Python interpreter to determine the data type. 
• The one exception to Python's object-oriented programming paradigm is the presence of access specifiers. Python has classes, inheritance, and many other common OOPs principles in addition to access specifiers whether public or private keywords.
• A Python program created on a Windows Machine will also run on a Linux system with little to no adjustments because Python is a cross-platform language. 
• Python is a general-purpose language in the truest sense of the word; as such, it is used in a wide range of fields including developing web applications, automation, machine learning, data science, and more. 

6. How does Python manage its memory?

Python's private heap space is responsible for managing memory. There is a private heap where all Python objects and data structures are kept. A programmer does not have access to this private heap; it is maintained by the Python Interpreter itself. The Python private heap area is allocated by the Python memory manager. The built-in Python garbage collector, which recycles and frees up all the unneeded memory, provides memory for the private heap space. 

7. Define PythonPath.

PythonPath performs a similar function as Path. This variable instructs the Python Interpreter where to find the imported module files. Both the directories containing Python source code and the Python source library should be included. The Python Installer will occasionally set PythonPath. 

8. How do Python Modules work?

Python Modules are the name given to files that contain Python Code. The programmer is given the predefined features when they are required by this code, which can either be classes, functions, or variables. It is an executable code file with the ".py" extension.

Below is a list of frequently used constructed modules: 

• Data
• Time
• Math
• Random
• OS 
• Sys
• Json

9. Explain Python Namespaces.

With the use of a Python namespace, object names in a program are made to be distinct and conflict-free. Python implements these namespaces as dictionaries with each namespace's corresponding object serving as the key.

Let's examine a few namespaces examples:

• Local namespace: within a function make up the local namespace. It is produced momentarily for a function call and cleared after the function completes.
• Global Namespace: The names in the global namespace come from various imported modules and packages currently being utilized in the project. Once the package is imported into the script, it is formed and exists till the script is executed.
• Built-in Namespace:  includes built-in Python core functions and unique built-in names for various exception types.

10. Describe Python Inheritance with Instances.

Classes in Python have the ability to inherit the properties of another class because it adheres to the object-oriented programming paradigm. Inheritance is the name given to this process. The feature of code reuse is provided by inheritance. Inheriting classes are referred to be superclasses or parent classes, while classes that do so are referred to as derived or child classes.

Python supports the following Inheritance:

• Single Inheritance:  A class inherits from a single superclass. 
• Multiple  Inheritance: Inheritance of multiple superclasses by a class
• Multilevel Inheritance: When a class derives from a superclass and another class subsequently derives from this derived class, a class structure known as "parent, child, and grandchild" is created.
• Hierarchical Inheritance: When several derived classes inherit from a single superclass.

11. Define Scope Resolution. 

In Python, a scope is a section of code where an object is still applicable. Every single Python object has a certain scope within which it operates. Although namespaces are used to uniquely identify each object in a program, these namespaces also have a defined scope where their objects may be used without a prefix. It establishes how long a variable is accessible. 

We may further comprehend this by taking a look at the scope that was established at the moment the code was executed: 

• The local objects present in the current function are referred to as being in a local scope.
• The items that are accessible throughout code execution are referred to as being in the global scope.
• The global objects connected to the program's current module are referred to as a module-level scope.
• All of the built-in names that can be called by the program are referred to as being in an outermost scope.

12. What does a Python dictionary mean?

One of the supported data types in Python is the dictionary. It consists of an unorganized group of components. Dictionary elements are saved as key-value pairs. Keys are used to index dictionaries.

13. What do Python Functions do?

A function is a section of code that is only run when it receives a call. The keyword def is used to specify a specific function. 

14. What does Python's __init__ mean?

In OOP terminology, the reserved function __init__ is equivalent to constructors in Python classes. Every time a new object is initiated, the __init__ method is automatically invoked. The new object is given memory as soon as it is created using this technique. Variables can also be initialized using this technique.

15. What are the typical Python built-in data types?

Python is compatible with the following built-in data types:

• Immutable data
• Number
• String
• Tuple
• Mutable Data Types
• List
• Dictionary 
• Set

16. Can you explain Python's local and global variables in brief?

Any variable declared inside a function is referred to as a local variable, and only that function has access to it. While Global variable means any variable defined outside of a function and any function found throughout the program can simply access it. 

17. What does Python's type conversion mean?

Python offers you the much-needed conversion capability, which allows you to change one data type into the one you require. 

Python's Type conversion can be classified in the following:

• Implicit Type Conversion: Here the Python interpreter assists in automatically transforming one data type into another data type without the involvement of the user.
• Explicit Type Conversion: In this type of type conversion, the user explicitly changes the data type into the desired type.

18. Is Python a case-sensitive language?

Yes. This also implies that both Function and function differ in Pythons like Pascal and SQL. 

19. Explain the methods of how to set a variable and Install Python Windows.

For installing Python on Windows, the following steps are to be taken:

• Click on a link that provides you downloadable Python Link and Installs Python
• After that, install it on your computer by using the command prompt to find the location where Python has been installed on your computer
• Go to the advanced system settings, add a new variable with the name PYTHON NAME, and then paste the path that was copied.
• Find the path variable by searching for it, choosing its value, and then choose "edit."
• If there isn't a semicolon at the end of the value, type%PYTHON HOME%.

20. What are packages in Python?

Python packages are numerous sub-packages and modules that are grouped or categorized depending on the similarity of the functions. 

21. What do Python decorators do?

Decorators are essential in Python since they operate to add functionality to an existing function without having to alter the structure. These are called bottom-up and are represented in Python by the @decorator name.

22. What distinguishes lists from arrays in Python?

Let us elaborate on the distinctions between Lists and Arrays in Python in the following points:

• The list is made up of elements with various data types.  While Arrays only include elements of the same data type.
• No module has to be imported for list declaration. However, a module must be imported specifically in order to declare an array. 
• The list can be nested to contain many types of elements while in Arrays all nested components must be similar in size. 
• List is recommended for shorter data sequences while arrays are recommended for longer data sequences.
• Lists are more adaptable to enable simple data updates whether addition or deletion while Array is less flexible because additions and deletions must be made element by element. 
• While huge amounts of memory are used in List for element addition, Array requires a significantly smaller memory footprint while inserting items. 
• List is totally printable without the use of loops. While in Array to print or access the components, a loop must be established.

23. Does Python require indentation?

Python requires indentation as a part of its syntax, and it is required. The scope and size of the block of codes can be defined in some way in all programming languages. Because it makes the code easier to read, Python presumably made indentation a requirement.

24. How do pass, continue, and break operate?

These statements are referred to as loop control statements since they assist in altering the execution phase relative to the usual flow.

Python break: This command helps end a loop or a statement and transfer control to the following command.

Python Continue: When a certain condition is met, the loop is forced to continue rather than being terminated by the Python continue statement.

Python pass: This statement aids in the syntactic construction of the code and seeks to forego execution. Given that nothing occurs when you implement the pass statement, it is also regarded as a null operation.

25. How do you remark in Python with numerous lines?

Python requires a line prefix of # before any comments that span several lines can be added.

26. Which of these languages is Python - Programming or Scripting?

Generally speaking, Python is a general-purpose programming language that may also be used for scripting.

27. Define Negative Indices and explain why are they used.

We only need to utilize the element's index, which is its position number, to access an element from an ordered sequence. Since the index typically begins at 0, the first element will have index 0, the second will have index 1, and so forth. 

Reverse indexing is the process of using the index to retrieve elements at the end of a list. When using reverse indexing, the last element with the index number "1" is where the indexing of the items begins. The index for the last element is "2," and so forth. Negative indexes are the ones used in reverse indexing.

Mid-Level Python Interview Questions and Answers

The following Python interview questions and answers are intermediate-level based concepts that are often asked in Python interviews spanning varied sectors

28. What do the split(), sub(), and subn() Python methods of the "re" module mean?

These methods are used to alter strings and are a part of the Python RegEx or "re" package. 

• Splitting a string into a list is done using the split() method.
• Substrings that match a regex pattern are found using the sub() method, which then substitutes the matching substring with a different string.
• Unlike the sub() method, which only produces the new string, subn() also returns the number of replacements.

29. What does Python's map function do?

Python's map() function takes two arguments: iterable and function. A function is supplied to the map() method as an argument, and that function is subsequently applied to all of the iterable's elements. An object list of results is returned.

30. What do Python generators do?

A generator is a function that produces an iterable set of objects.

31. What are Python iterators, exactly?

These are the specific things that can be quickly navigated and iterated over as necessary.

32. Do Python variables need to be declared with their data types?

No. Python is a dynamically typed language, meaning that the Python Interpreter determines a variable's data type based on the kind of value it has been given to the variable. 

33. Explain Dicta and Lists comprehensions.

Similar to decorators, Python comprehensions assist in creating modified and filtered lists, dictionaries, or sets from a given list, dictionary, or set. Time and potentially far more complex and time-consuming code are saved by comprehension.

The following scenarios call for comprehension:

• Putting all the list's items via a mathematical operation 
• Operating on the entire list with conditional filtering
• Combining several lists into a single one
• Flattening lists of multidimensional

34. How should comments be written in Python?

Python comments are statements that programmers use to make their code easier to read. You can define a single comment with the help of #, and you can also comment using docstrings (strings enclosed within triple quotes).

 For instance:

 #Comments in Python

  print("Comments in Python ")

35. Is Python capable of supporting multiple Inheritance?

Yes, Python offers users a wide range of support for inheritance and its application, unlike Java. When a class is created from more than one distinct parent class, this is referred to as multiple inheritance. Users benefit from a lot of functionality and advantages. 

36. Define pickling and unpickling?

The Python object is accepted by the Pickle module, which then uses the dump method to transform it into a string representation and store it in a file. Pickling is the name of this procedure. On the other side, unpickling refers to the act of obtaining the original Python objects from the string representation.

37. What does Tkinter mean to you?

A built-in Python package called Tkinter is used to make GUI applications. It is the default toolkit for Python GUI programming. There is no need for a separate installation because Tkinter is included with Python. Importing it into your script will allow you to use it immediately.

38. Is Python entirely object-oriented?

Apart from access specifiers, Python does adhere to the paradigm of object-oriented programming and has all of the fundamental OOPs principles, including inheritance, polymorphism, and more. Strong encapsulation is not supported by Python (adding a private keyword before data members). However, it does have a convention for data concealing, which is to prefix a data item with two underscores.

39. Distinguish between SciPy and NumPy?

Let us consider a few of these points below to distinguish between  SciPy and NumPy:

Numerical Python is referred to as NumPy. Scientific Python is the official name for SciPy.

For efficient and all-purpose numerical computations on numerical data saved in arrays, NumPy is employed. Sorting, indexing, reshaping, and other processes SciPy is a set of Python-based tools for carrying out operations including differentiation, integration, and more.

Although NumPy offers certain linear algebraic functions, they are not fully featured.

For algebraic computations, SciPy offers full-featured algebraic functions.

40. What do Python modules that deal with files do? Can you list some Python modules that deal with files?

Python has a few file-related modules with tools for working with both text and binary files in a file system. These modules provide for the creation of texts or binary files, as well as for updating, copying, deleting, and other operations.

A few of the modules that deal with files are:

• os
• os. path
• shutil.os 

Whereas the shutil.os module can be utilized to copy or remove files, the os. path module includes functions for accessing the file system.

41. What functions do the operators is, not, and in perform?

The term "operator" refers to a specific function that accepts one or more operands (values) and returns a related result.

is: returns true when both operands are true. For instance "x" is "x"

not: Based on the operands, this function returns the opposite of the boolean value. For instance "1" returns "0" and vice versa.

in: Assists in determining whether an element is present in a given sequence. 

42. In the event of Python exiting, why are the memories not de-allocated

These Python modules particularly those that have circular references to other objects or that reference objects from the global namespaces are not always de-allocated or deleted when Python exits. Particularly those Python modules that have circular references to other objects or that reference objects from the global namespaces are not always de-allocated or deleted when Python quits. De-allocating the memory blocks that the C library has reserved is not possible.

Python would attempt to de-allocate every object upon exit due to its own effective cleanup mechanism.

43. Define Python Slicing.

 Accessing individual elements of sequences such as lists, tuples, and strings is done using slicing. Slicing has the syntax [ start:end:step]. The action may also be skipped. When we write [start: end], it returns all of the sequence's members up until element end-1, inclusive. It means the ith element from the end if either the start or end element is negative i. The step describes the jump or the number of components that must be omitted. For instance, 

[1,2,3,4,5,6,7,8] if there is a list. Then, by printing every second element, [-1:2:2] will return elements beginning from the last element and going all the way up to the third element. i.e. [8,6,4].

44. What are Literals in Python? Please describe the various Literals.

For basic data types, a literal in Python source code denotes a fixed value. Python has five different sorts of literal:

String Literal: To produce this literal, a variable is assigned some text enclosed in quotes either single or double. The multiline text should be enclosed in triple quotes to produce multiline literal.

Character Literal:  A character literal is generated by assigning a character in double quotes. 

Numeric Literals: An integer, a floating point value, or a complex number can all be used as numeric literals. 

Boolean literals: These have only two possible values: True or False

Literal Collections: This literal consists of four types namely: List collections, Tuple literals, Dictionary literals, and Set Literals. 

45. Define self in Python

This is included as the first parameter in Python directly. 

In Java, it is optional, thus this is not the case. 

Using local variables makes it easier to distinguish between a class's methods and attributes. In other methods, the self variable refers to the object whose method was called, however in the init method, it refers to the freshly formed object.

46. Describe the process of removing values from Python Array

To remove components from the array, the functions pop () and remove () can be used. 

pop(): This method will bring back the element that was removed.

remove(): It won't bring back the piece that was removed.

47. Why would you use Python's NumPy arrays over lists?

Users benefit from three key advantages of NumPy arrays, as seen below:

Because NumPy arrays use much less memory, the code is more effective.

NumPy arrays run more quickly and don't require a lot of runtime processing.

Because of its very legible syntax, NumPy is simple and practical for programmers.

48. What Does Python's Polymorphism Mean?

The capacity of the code to take various forms is known as polymorphism. Consider the scenario where the parent class has a method called XYZ and the child class is able to have a method with the same name but different variables and parameters.

49. What does Python's encapsulation mean?

In Python, the term "encapsulation" refers to the act of combining various functions and variables into a single unit. Python Class would be the best instance for Python encapsulation. 

50. What distinguishes deep copy from shallow copy?

When a new instance type is formed, a shallow copy is employed, keeping the copied values in the new instance. A shallow copy is utilized to copy reference points in a manner akin to how it replicates values. Because these references point to the original objects, any changes made to a class member will also affect the original copy of the class. 

Deep copies are used to store previously duplicated values. During the deep copy, the links to the objects are not copied. Shallow copy improves program performance and is dependent on the quantity of data being used. The new object, which is referenced by another object, is stored along with the newly created object reference. The changes made to the original copy won't have an effect on any additional copies that make use of the object. Since deep copy creates individual copies of each object that is called, it slows down program execution.

Advanced-level Python Interview Questions and Answers

51. What does Python's lambda function do?

In Python, an anonymous function—one without a name—is referred to as a lambda function. The term "lambda function" refers to the usage of the "lambda" keyword in place of the "def" keyword to define anonymous functions. Lambda functions only allow one statement and any number of parameters.

52. What distinguishes the methods extend() and append()?

In order to add elements to the end of a list, you can use the append() and extend() methods.

Append(element)- Adds the specified element to the end of the list which is called this append() method.

Extend(another list) method adds the entries of another list to the end of the list that is called it.

53. What database requests are handled by Python Flask?

A database-powered application is supported by Flask (RDBS). A schema must be created for such a system, and the schema.sql file must be piped into the sqlite3 command. To construct or launch the database in Flask, Python programmers must install the sqlite3 command.

There are three ways that Flask enables database requests:

Before request() calls are made without passing any arguments.

After request(): These functions are used to handle requests and provide the response to the client.

Teardown request() is used when an exception is thrown and a guarantee of a response is not possible. They are contacted following the creation of the answer. Their values are disregarded, and they are not permitted to alter the request.

54. What is a Flask and what are its advantages?

A web microframework for Python called Flask is built on the BSD license and uses Werkzeug, Jinja2, and good intents. They rely on Werkzeug and Jinja2, among other things. This means that its reliance on outside libraries will be minimal to nonexistent. The framework becomes lighter while requiring less updating effort and having fewer security flaws.

In essence, a session enables you to retain knowledge from one request to the next. A session in a flask employs a signed cookie to allow the user to view and alter the contents of the session. If the user only has the secret key Flask.secret key, they can change the session.

55. Is Flask superior to Django?

The URLs or addresses entered into web browsers are translated into Python functions by Django and Flask.

Despite being considerably simpler than Django, Flask requires you to describe a lot of the specifics, whereas Django handles a lot of the work for you so that you don't have to. Django uses prewritten code, which the user must evaluate, whereas Flask allows users to write their own code, which makes it easier to comprehend. Technically speaking, both are excellent and have their own advantages and disadvantages.

56. Mention the variations between Flask, Pyramid, and Django.

A "micro-framework" called Flask is designed primarily for small applications with straightforward needs. You must utilize external libraries with flask. Use the flask now.

The pyramid was designed for more extensive uses. The developer can choose the best tools for their project because of their versatility. The database, URL structure, templating style, and other options are all up to the developer. a heavy-duty customizable pyramid

Like Pyramid, Django may be applied to larger applications. It contains an ORM.

57. What does Python's docstring mean?

Python users can utilize documentation strings, also known as docstrings, to give a description (or brief notes), for their methods. Docstrings differ from conventional comments in Python in that they are defined within triple quotes, as opposed to comments, which the Python Interpreter entirely ignores.

58. What does Python's "monkey patching" mean?

The term "monkey patching" is used to describe changes made to a class or module during runtime. Python only allows program behavior to change while it is being run, thus this is the only way to do it.

59. Describe pandas.

Pandas is a free and open-source library for Python that supports data structures for operations on data that are related to data analysis and data manipulation. With its extensive feature set, Pandas may be used for every type of data operation, whether it's for developing various algorithms or resolving challenging business issues. Pandas assists in handling multiple files when carrying out specific operations on the data that files store.

60. How does Python handle data abstraction?

The answer is that data abstraction conceals the implementation from the public and only provides the necessary information. In Python, it can be done by utilizing abstract classes and interfaces.

61. Does Python employ access specifiers?

Python does not restrict access to a function or instance variable. In order to mimic the functionality of protected and private access specifiers, Python introduces the concept of prefixing the name of the variable, function, or method with a single or double underscore.

62. Explain the creation of an empty Python Class. 

An empty class is one that has no defined code within its block. It can be produced by using the pass keyword. Despite the fact that you can create these class objects outside of the class. The PASS command does not do anything in Python. It becomes a null assertion or statement. 

63. Describe the function of an object ()

A featureless object that serves as the base for all classes is returned. Furthermore, it doesn't require any parameters.

Programming-based Python Interview Questions and Answers

64. Can you write a Python program for Checking if a number is prime?

1 a=int(input("enter number"))

2 if a=1:

3 for x in range(2,a):

4 if(a%x)==0:

5 print("not prime")

6 break

7 else:

8 print("Prime")

9 else:

10 print("not prime")

65. How can I create a Python sorting algorithm for a numerical dataset?

Python code for list sorting:

my_list = ["8", "4", "3", "6", "2"]

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

my_list.sort()

print (my_list)

66. Write a program for converting dates from the yyyy-mm-dd format to the dd-mm-yyyy format.

The date string can be converted using the re module as illustrated below:

import re

def transform_date_format(date):

   return re.sub(r'(\d{4})-(\d{1,2})-(\d{1,2})', '\\3-\\2-\\1', date)

date_input = "2021-08-01"

print(transform_date_format(date_input))

67. Create a program to match strings containing the letter "a" and 4 to 8 "bs."

Here, we may compare regex patterns using Python's re package.

import re

def match_text(txt_data):

       pattern = 'ab{4,8}'

       if re.search(pattern,  txt_data):    #search for pattern in txt_data

           return 'Match found'

       else:

           return('Match not found')

print(match_text("abc"))         #prints Match not found

print(match_text("aabbbbbc"))    #prints Match found

68. Create a program that counts each character in a given text file.

The concept is to use the pprint module and collections as illustrated below:

import collections

import pprint

with open("sample_file.txt", 'r') as data:

 count_data = collections.Counter(data.read().upper())

 count_value = pprint.pformat(count_data)

print(count_value)

69. Without utilizing the plus operator, create a program to add two integers that are greater than 0.

To accomplish this, we can employ bitwise operators.

def add_nums(num1, num2):

   while num2 != 0:

       data = num1 & num2

       num1 = num1 ^ num2

       num2 = data 

70. What is the longest identifier that can be used?

Identifiers are not limited in length.

71. Why is it not recommended to start local variable names with an underscore?

They serve as a class's private variable designation. Leading underscores are applied to denote variables that should not be accessible from outside the class because Python does not have the concept of private variables.

72. Compute a program in Python to print ASCII Value of a character 

x= 'a'

# print the ASCII value of assigned character stored in x

print(" ASCII value of '" + x + "' is", ord(x))

73. Using NumPy/SciPy, how do you create 3D charts or visualizations?

Just like with 2D charting, 3D graphics are outside of the purview of NumPy and SciPy, but just like with 2D plotting, packages that interface with NumPy are available. When using the sophisticated VTK engine, Mayavi offers a wide range of high-quality 3D visualization options, in contrast to Matplotlib's rudimentary 3D charting capabilities in the mplot3d subpackage.

74. Define classifier.

A classifier can predict the class of any data point. Classifiers are theories that are used to categorize data objects and then assign labels to those data pieces.

75. How will you differentiate Python 2.x from Python 3.x?

An older version of the Python programming language is called Python 2.x. The most recent version is Python 3.x. Python 2.x no longer receives support. The present and future of the language are in Python 3.x. A string is always ASCII in Python2, but Unicode in Python 3.

76. In Python, how do you send an email?

Python has email and smtplib libraries that can be used to send emails. Send emails to people who have been authenticated by importing these modules into the freshly created mail script.

77. In Python, how do you write a Unicode string?

In Python 3, the "str" type has taken the place of the previous "unicode" type, and the string is now by default Unicode. We may generate a Unicode string by using the function art.title.encode("utf-8").

78. What types of joins do Pandas offer?

Pandas supports the left, inner, right, and outer joins.

79. How are data frames combined in Pandas?

How two data frames are combined depends on the type and fields of each. The data is combined along axis 0 if all of its fields are similar; otherwise, it is merged along axis 1.

80. How can you acquire a data frame's initial five entries in the best way possible?

The head(5) technique enables us to obtain the first five entries in a data frame. By default, df.head() returns the top 5 rows. The top n rows will be fetched using df.head(n).

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