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Python Conditional Statements

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Python Loops

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Python Functions

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Python OOPs Concept

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Python Iterators

Iterators in Python Yield Statement In Python

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Python 3

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Misc

Python PPTX Python Pickle Python Seaborn Python Coroutine Python EOL Python Infinity Python math.cos and math.acos function Python Project Ideas Based On Django Reverse a String in Python Reverse a Number in Python Python Word Tokenizer Python Trigonometric Functions Python try catch exception GUI Calculator in Python Implementing geometric shapes into the game in python Installing Packages in Python Python Try Except Python Sending Email Socket Programming in Python Python CGI Programming Python Data Structures Python abstract class Python Compiler Python K-Means Clustering NSE Tools In Python Operator Module In Python Palindrome In Python Permutations in Python Pillow Python introduction and setup Python Functionalities of Pillow Module Python Argmin Python whois Python JSON Schema Python lock Return Statement In Python Reverse a sentence In Python tell() function in Python Why learn Python? Write Dictionary to CSV in Python Write a String in Python Binary Search Visualization using Pygame in Python Latest Project Ideas using Python 2022 Closest Pair of Points in Python ComboBox in Python Python vs R Best resources to learn Numpy and Pandas in python Check Letter in a String Python Python Console Python Control Statements Convert Float to Int in Python using Pandas Difference between python list and tuple Importing Numpy in Pycharm Python Key Error Python NewLine Python tokens and character set Python Strong Number any() Keyword in python Best Database in Python Check whether dir is empty or not in python Comments in the Python Programming Language Convert int to Float in Python using Pandas Decision Tree Classification in Python End Parameter in python __GETITEM__ and __SETITEM__ in Python Python Namespace Python GUI Programming List Assignment Index out of Range in Python List Iteration in Python List Index out of Range Python for Loop List Subtract in Python Python Empty Tuple Python Escape Characters Sentence to python vector Slicing of a String in Python Executing Shell Commands in Python Genetic Algorithm in python Get index of element in array in python Looping through Data Frame in Python Syntax of Map function in Python After Python What Should I Learn Python AIOHTTP Alexa Python Artificial intelligence mini projects ideas in python Artificial intelligence mini projects with source code in Python Find whether the given stringnumber is palindrome or not First Unique Character in a String Python Python Network Programming Python Interface Python Multithreading Python Interpreter Data Distribution in python Flutter with tensor flow in python Front end in python Iterate a Dictionary in Python Iterate a Dictionary in Python – Part 2 Allocate a minimum number of pages in python Assertion Errors and Attribute Errors in Python Checking whether a String Contains a Set of Characters in python Python Control Flow Statements *Args and **Kwargs in Python Bar Plot in Python Conditional Expressions in Python Function annotations() in Python How to Write a Configuration file in Python Image to Text in python import() Function in Python Import py file in Python Multiple Linear Regression using Python Nested Tuple in Python Python String Negative Indexing Reading a File Line by Line in Python Python Comment Block Base Case in Recursive function python ER diagram of the Bank Management System in python Image to NumPy Arrays in Python NOT IN operator in Python One Liner If-Else Statements in Python Sklearn in Python Python Ternary Operators Self in Python Python vs Java Python Modulo Python Packages Python Syntax Python Uses Python Bitwise Operators Python Identifiers Python Matrix Multiplication Python AND Operator Python Logical Operators Python Multiprocessing Python Unit Testing __init__ in Python Advantages of Python Is Python Case-sensitive when Dealing with Identifiers Python Boolean Python Call Function Python History Python Image Processing Python main() function Python Permutations and Combinations Difference between Input() and raw_input() functions in Python Conditional Statements in python Confusion Matrix Visualization Python Python Algorithms Python Modules List Difference between Python 2 and Python 3 Is Python Case Sensitive Method Overloading in Python Python Arithmetic Operators Assignment Operators in Python Is Python Object Oriented Programming language Division in Python Python exit commands Continue And Pass Statements In Python Colors In Python Convert String Into Int In Python Convert String To Binary In Python Convert Uppercase To Lowercase In Python Convert XML To JSON In Python Converting Set To List In Python Covariance In Python CSV Module In Python Decision Tree In Python Difference Between Yield And Return In Python Dynamic Typing In Python

How to

How to Substring a String in Python How to Iterate through a Dictionary in Python How to convert integer to float in Python How to reverse a string in Python How to take input in Python How to install Python in Windows How to install Python in Ubuntu How to install PIP in Python How to call a function in Python How to download Python How to comment multiple lines in Python How to create a file in Python How to create a list in Python How to declare array in Python How to clear screen in Python How to convert string to list in Python How to take multiple inputs in Python How to write a program in Python How to compare two strings in Python How to create a dictionary in Python How to create an array in Python How to update Python How to compare two lists in Python How to concatenate two strings in Python How to print pattern in Python How to check data type in python How to slice a list in python How to implement classifiers in Python How To Print Colored Text in Python How to develop a game in python How to print in same line in python How to create a class in python How to find square root in python How to import numy in python How to import pandas in python How to uninstall python How to upgrade PIP in python How to append a string in python How to open a file in python How to Open a file in python with Path How to run a Python file in CMD How to change the names of Columns in Python How to Concat two Dataframes in Python How to Iterate a List in Python How to learn python Online How to Make an App with Python

Sorting

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Programs

Factorial Program in Python Prime Number Program in Python Fibonacci Series Program in Python Leap Year Program in Python Palindrome Program in Python Check Palindrome In Python Calculator Program in Python Armstrong Number Program in Python Python Program to add two numbers Anagram Program in Python Even Odd Program in Python GCD Program in Python Python Exit Program Python Program to check Leap Year Operator Overloading in Python Pointers in Python Python Not Equal Operator Raise Exception in Python Salary of Python Developers in India What is a Script in Python

Classes & Objects in Python

Classes and Objects are used in most modern programming languages, mainly in Object-oriented Programming languages.

What is meant by Object Oriented Programming language?

Usage of objects and their components in order to create a software program is known as Object-oriented Programming language. More shortly, it is known as OOP.

                                                (or)

The name itself specifies what it is actually. A language that is completely oriented with Objects and Components of objects is known as an Object-oriented programming language. Ex: Python, C++, Java.

As we have already discussed, Python is also such type of programming, i.e., Object-oriented programming. Classes and objects can be created fully, only in Object-Oriented Languages.

What is a class?

A class is a blueprint with a similar functionality where objects can be created or declared. A class is generally created using the keyword "class".

Syntax for creating a class:

class ClassName:

Example program for creating a class:

class Program:
    n= 20
    print(n)

Output:

10

What do a class contain?

A class consists of Objects, Attributes, Methods and Constructors.

Classes & Objects in Python

Why do we use classes?

The classes allow logical grouping of the data and function to make understanding and implementation easier. Here, data is nothing but Attributes. Functions are nothing but methods. A method is a function associated with its specific class.

Classes also allow reusability. Small changes can lead to different implementations and different outputs. This is the main use of class. The program can be changed easily for better implementations while using classes.

Let's discuss classes and their components with a real-time example.

Consider a class consisting of 60 students. Every student has their own identity. They have different names, different ages, different genders, belong to different regions, etc. There are many aspects that should be considered and makes every student unique. Every student might not be similar.

Some might function sharp, some might be low, some might be hyper active, etc. So, here class will be “Student”. Attributes are “name”, “age”, “gender”, “region”, etc. Methods are “sharp()”, “low()”, “hyperactive()”, etc. Objects will be “student1”, “student2”, “student3”, “student4”, ………. “student59”,” student60”.

What is an Object?

An instance of a class is known as an Object. An object is declared within the class to call any of the methods or access the attributes present in that particular class. Therefore, the creation of an object in a class is known as the Instantiation of the class.

Syntax for creating an Object:

#object is being created
obj1 = ClassName()

The one mentioned above is the basic structure/syntax of the creation of objects. This is insufficient for creating objects in a particular class. We are supposed to use the __init__() functionto create objects in a class.

__init__ () function:

It is a built-in function that should be used if we want to create or declare objects within the class. In other words, we can say that the __ init __() function helps in the initiation of the class. All the operations that are supposed to be done while or after initiating an object are done by the __ init __() function. The keyword “self” must be given as a parameter within the function parenthesis. The same object will be called when a method is called along with the parameters. That's the indication of self as a parameter.

Ex: When the object started calling the parameterized method, i.e.,

object.method( par1, par2),

then, the actual thing that happens is Class.method(object,par1, par2). The indication of the object within the parameters is “self”.

Syntax for __init__ () function:

class ClassName:
    def __init__(self,parameter1,parameter2,parameter3,.........,parametern):
        self.parameter1=parameter1
        self.parameter2=parameter2
        .......
        self.parametern=parametern
obj1 = ClassName()

Example program using init() and self:

class Student:
    def __init__(self,name,age,gender):
        self.name=name
        self.age=age
        self.gender=gender
obj1=Student("Sathwik","20","Male")
print(obj1.gender)
print(obj1.name)

Output:

Male
Sathwik

Let's try a similar example without using self.

Example program using init() without self:

class Garage:
    def __init__(obj1,company,colour):
        obj1.company=company
        obj1.colour=colour
obj1=Garage("Swift","Black")
print("The car "+obj1.colour+" "+obj1.company+" is out for delivery.")
print("You are pleased to collect it from the garage.")

Output:

The car Black Swift is out for delivery.
You are pleased to collect it from the garage.

Explanation:

As we all know that the "self" represents the object created within the class, we have used the same object instead of “self” in the second example. We got the output without any errors. Initially, the object is initiated using the init method inside the class, and the object is declared after assigning parameters. Printing the statements gave no errors, as-like the first example.

Example program which defines Creation of Class, Creation of Object, usage of init function and usage of self:

class Employee:
    def __init__(self,name,gender,salary,age,place):
        self.name=name
        self.gender=gender
        self.salary=salary
        self.age=age
        self.place=place
obj1=Employee("Sannah","She","50000","23","Hyderabad")
print(obj1.name+" is earning "+obj1.salary+" per month.")
print(obj1.name+" is "+obj1.age+" years old.")
print(obj1.gender+" is from "+obj1.place)

Output:

Sannah is earning 50000 per month.
Sannah is 23 years old.
She is from Hyderabad

Explanation:

Initially, a class named Employee is created in order to note the details of Employees working in that company. Init method is defined or initiated considering the parameters, i.e., name, gender, salary, age, place and (default parameter) self. All the parameters are converted into attributes, and then instantiation of object obj1 is implemented. The values have been given to the parameters within the object creation and then allowed to print the statements.

Operations that can be performed 1) Using objects and 2) On objects:

  • Modify values of attributes:
    If the initial value of an attribute is set to a value, then using objects, we can change or modify the value of that attribute for that particular instance. It can be done by using objects.

Syntax:

class Numbers:
    def __init__(self,name):
        self.name=name
        number=2
obj1=Numbers("Hello")
obj1.number=6
print("My name is "+obj1.name)
print("The changed number is ")
print(obj1.number)

Output:

My name is Hello
The changed number is
6

Explanation:

Initially, the value of "number" is set to 2 inside the init method of the class Numbers. Outside the method, we changed the value of " number" using the object and set it to 6. After changing it, we have allowed it to be printed. From the output, we can say that the value of the attribute has been changed.

  • Deletion of Objects:
    The syntax is very simple. The objects can be deleted by using the keyword "del". This operation can be performed anywhere after the object has been initiated in the code.

Syntax:

del object_name

Example program to determine the deletion of an object:

class Places:
    def __init__(self,name):
        self.name=name
    
obj1=Places("Hyderabad")
del obj1

Output:

Traceback (most recent call last):
  File "d:\downloads hdd\2-2\test.py", line 7, in <module>
    print("I live in "+obj1.name)
NameError: name 'obj1' is not defined

Explanation:

Initially, the object is created under the class Places. A string value for the name parameter “Hyderabad” is passed through that object. But the object is deleted right after that and allowed to print. As the print statement is given after the object deletion, an error has been raised, i.e., NameError defining that the desired object is not found. Let us check out the output of the same program without object deletion.

class Places:
    def __init__(self,name):
        self.name=name
    
obj1=Places("Hyderabad")
#Changing the delete statement into comment and checking for the output
#del obj1
print("I live in "+obj1.name)

Output:

I live in Hyderabad
  • Delete Attributes or Object properties:
    Like the deletion of objects, the attributes can also be deleted anywhere in the program after declaration.

Syntax:

del object_name. attribute

Example program determining the deletion of Attributes using objects:

class Hi:
    def __init__(self,name):
        self.name=name
    number=20
obj1=Hi("Nikki")
del obj1.number


print("The number present in the class Hi is ")
print(obj1.number)

Output:

Traceback (most recent call last):
  File "d:\downloads hdd\2-2\test.py", line 6, in <module>
    del obj1.number
AttributeError: number

Explanation:

Initially, the object is created under the class Hi. A string value for the name parameter “Nikki” is passed through that object. Along with the valued parameter, an attribute “number” is also declared before initiating the object. But the attribute is deleted concerning the object right after being initiated and allowed to print. As the print statement is given after the attribute deletion, an error has been raised, i.e., AttributeError, which defines that the desired attribute is not found. Let us check out the output of the same program without attribute deletion.

class Hi:
    def __init__(self,name):
        self.name=name
    number=20
obj1=Hi("Nikki")
#changing the delete statement into comment and checking for the output
#del obj1.number
print("Hi, my name is "+obj1.name)
print("The number present in the class Hi is ")
print(obj1.number)


Output:

Hi, my name is Nikki
The number present in the class Hi is 
20



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