Python Tutorial

Introduction Python Features Python Applications System requirements for Python Python Installation Python Basics Python Variables Python Data Types Python IDE Python Keywords Python Operators Python Comments Python Pass Statement

Python Conditional Statements

Python if Statement Python elif Statement Python If-else statement Python Switch Case

Python Loops

Python for loop Python while loop Python Break Statement Python Continue Statement Python Goto Statement

Python Arrays

Python Array Python Matrix

Python Strings

Python Strings Python Regex

Python Built-in Data Structure

Python Lists Python Tuples Python Lists vs Tuples Python Dictionary Python Sets

Python Functions

Python Function Python min() function Python max() function Python User-define Functions Python Built-in Functions Anonymous/Lambda Function in Python

Python File Handling

Python File Handling Python Read CSV Python Write CSV Python Read Excel Python Write Excel Python Read Text File Python Write Text File Read JSON File in Python

Python Exception Handling

Python Exception Handling Python Errors and exceptions Python Assert

Python OOPs Concept

OOPs Concepts in Python Classes & Objects in Python Inheritance in Python Polymorphism in Python Python Encapsulation Python Constructor Static Variables in Python Abstraction in Python

Python Iterators

Iterators in Python Yield Statement In Python

Python Generators

Python Generator

Python Decorators

Python Decorator

Python Functions and Methods

Python Built-in Functions Python String Methods Python List Methods Python Dictionary Methods Python Tuple Methods Python Set Methods

Python Modules

Python Modules Python Datetime Module Python Calendar Module  

Python MySQL

Python MySQL Python MySQL Update Operation Python MySQL Delete Operation

Python MongoDB

Python MongoDB

Python Data Structure Implementation

Python Stack Python Queue Python Hash Table Python Graph

Python Advance Topics

Speech Recognition in Python Face Recognition in Python Python Rest API Python Command Line Arguments Python JSON Python Virtual Environment Type Casting in Python Collections in python Python Enumerate Python Debugger Python DefaultDict

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 List Comprehension in Python3 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 Python Ternary Operators Self in Python Python vs Java Python Modulo Python Packages Python Syntax Python Uses Python Logical Operators Python Multiprocessing Python History 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 Design patterns in python 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 Abstract design pattern in python Builder design pattern in python Prototype design pattern in Python Creational design patterns in Python

How to

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

Sorting

Python Sort List Sort Dictionary in Python Python sort() function Python Bubble Sort

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 Singleton design pattern in python

How to create a dictionary in Python?

How to create a dictionary in python

Dictionary is a data structure in Python that represents our data in the form of keys and values.

Each value in a dictionary can be accessed using its corresponding key.

Let us have a look at some more properties of a Dictionary-

  1. All the keys in a dictionary should be unique.
  2. The keys in the dictionary are case-sensitive which means 'shape' and 'SHAPE' are treated as two different keys.

Let us have a look that how we can create a dictionary in Python-

Syntax of Dictionary

a={'Fruit_name':'Apple','Color':'Red','Shape':'Spherical'}

Now let’s see after creating it how we can verify this data structure.

The following program illustrates how we can check the type-

 #using dictionary
 a={'Fruit_name':'Apple','Color':'Red','Shape':'Spherical'}
 print(a)
 print(type(a)) 

INPUT-

OUTPUT-

In the output, we can observe the dictionary ‘a’ is printed that contains three keys and type() returns its datatype.

The next thing that we will discuss in this article is how we can access the values in our dictionary.

Accessing values in a dictionary

In the following program, we have used the keys to access the values of our dictionary.

 #using dictionary
 a={'Fruit_name':'Apple','Color':'Red','Shape':'Spherical'}
 print(a)
 print(type(a))
 #accessing elements using keys
 print(a['Fruit_name'])
 print(a['Color'])
 print(a['Shape']) 

INPUT-

OUTPUT-

In the output, we can observe the following things-

  1. The dictionary ‘a’ is printed.
  2. The data type is returned which is <class ‘dict’>.
  3. Then the three values are displayed when we access them using the keys 'Fruit-Name', 'Color', and 'Shape'.

Now, let us see what are the different ways of creating a dictionary in Python.

WAYS TO CREATE A DICTIONARY

Here, we will try to understand this with the help of four methods-

  1. Simple creation of a list
  2. Using dict()
  3. Using {}
  4. Using defaultdict

In the first method, we can see a dictionary is created using the most basic approach where we have specified our keys and values in the curly braces.

Following program illustrates the same.

 #creating a dictionary
 a={'Fruit_name':'Apple','Color':'Red','Shape':'Spherical'}
 print(a)
 print("The type of a is {}".format(type(a))) 

INPUT-

OUTPUT-

On executing the given program, the expected results are displayed.

The second method that we will discuss here is creating a dictionary using dict().

So, here we have declared object a as dict() and then defined our dictionary.

Following program illustrates the same-

 #creating a dictionary
 a=dict()
 a={'Fruit_name':'Apple','Color':'Red','Shape':'Spherical'}
 print(a)
 print("The type of a is {}".format(type(a))) 

INPUT-

OUTPUT-

On executing the code, the expected results are displayed.

The third method that we will discuss is creating a dictionary by declaring a as {} and then defining the value for each key.

Then we have printed a and its data type.

Following program illustrates the same-

 #creating a dictionary
 a={}
 a["Fruit_Name"]="Apple"
 a["Color"]="Red"
 a["Shape"]="Spherical"
 print(a)
 print("The type of a is {}".format(type(a))) 

INPUT-

OUTPUT-

The last method that we will discuss is creating a dictionary using defaultdict().

Here we have provided a list that contains the key, value pairs and then applied the method defaultdict() to it and then added each value corresponding to the key, and then printed it.

Following program illustrates the same-

 #using defaultdict
 from collections import defaultdict
 lst=[('Fruit_Name','Apple'),('Color','Red'),('Shape','Spherical'),('Fruit_Name','Grapes')]
 dict_fruits=defaultdict(list)
 for key,value in lst:
     dict_fruits[key].append(value)
 print(dict_fruits) 

INPUT-

OUTPUT-

In the output, we can observe that first of all it tells us that it belongs to the <class 'list'> which is followed by a dictionary that has the keys and all the values are in the form of lists.

The next thing we will discuss in this article is how we add and modify the values in our dictionary.

Updating dictionary

Let us first see how we can add an element in the dictionary.

Following program illustrates the same-

 #adding an element in dictionary
 a={'Fruit_Name':'Apple','Color':'Red','Shape':'Spherical'}
 print(a)
 print("The type of a is {}".format(type(a)))
 a['Fruit_Name1']='Grapes'
 print(a) 

INPUT-

OUTPUT-

In the output, we can observe the new key-value pair being added.

Next, we will see how we can modify the value of a particular key.

Following program illustrates the same-

 #modifying an element in dictionary
 a={'Fruit_Name':'Apple','Color':'Red','Shape':'Spherical'}
 print(a)
 print("The type of a is {}".format(type(a)))
 a['Color']='Green'
 print(a) 

INPUT-

OUTPUT-

In the output, we can observe the value of color has been modified from ‘Red’ to ‘Green’.

In the last section of this article, we will take a brief idea of the methods that are used in a dictionary.

Methods used in Dictionary

  1. len() – The len() method returns the length of our dictionary. In the output, we can see that it comes out to be 3.
 #methods on dictionary
 a={'Fruit_Name':'Apple','Color':'Red','Shape':'Spherical'}
 print(len(a)) 
  • Dict.get(‘key’)-In this ‘Dict’ refers to the name of the dictionary and ‘key’ refers to the name of the key whose value we would like to fetch. We can see in the example it returns ‘Red’ when we provide the key ‘Color’.
 #methods on dictionary
 a={'Fruit_Name':'Apple','Color':'Red','Shape':'Spherical'}
 print(a.get('Color')) 
  • Dict.items()-In this method, ‘Dict’ refers to the name of the dictionary and it returns all the key-value pairs present in the dictionary.
 #methods on dictionary
 a={'Fruit_Name':'Apple','Color':'Red','Shape':'Spherical'}
 print(a.items()) 
  • Dict.keys()-In this method, 'Dict' refers to the name of the dictionary and it returns all the keys present in the dictionary. In the output, we can see it returns the keys 'Fruit_Name', 'Color', and 'Shape'.
 #methods on dictionary
 a={'Fruit_Name':'Apple','Color':'Red','Shape':'Spherical'}
 print(a.keys()) 
  • Dict.values()-In this method, ‘Dict’ refers to the name of the dictionary and it returns all the values present in the dictionary. In the output, we can see it returns the values ‘Apple’,’Red’ and ‘Spherical’.
 #methods on dictionary
 a={'Fruit_Name':'Apple','Color':'Red','Shape':'Spherical'}
 print(a.values()) 

So, in this article, we discussed dictionaries, how we can access them, how we can create them, and what are the different methods that we can apply to them.



ADVERTISEMENT
ADVERTISEMENT