How to create a dictionary in Python?

Data Science, AI and ML
#1

A Python dictionary is stored the data in the pair of key-value. It organizes the data in a unique manner where some specific value exists for some particular key. It is a mutable data-structure; its element can be modified after creation. Before creating a dictionary, we should remember the following points.

  • Keys must be unique and must contain a single value.
  • Values can be any type, such as integer, list, tuple, string, etc.
  • Keys must be immutable.

Creating a Dictionary

The dictionary is created using the multiple key-value pair, which enclosed within the curly brackets {}, and each key is separated from its value by the colon (:). The syntax is given below.

Syntax:

dict1 = {“Name”: “James”, “Age”: 25, “Rollnu”: 0090001 }
In the above dictionary, the Name, Age, Rollnu are the keys which immutable object and James, 25, 0090001 are its values.

Let’s see the following example.

Example -

Student = {"Name": "John", "Age": 10, "Result":"Passed","Rollno":"009001"}  
print(type(Student))  
print("printing Employee data .... ")  
print(Student)

Output:

<class 'dict'>
printing Employee data .... 
{'Name': 'John', 'Age': 10, 'Result': 'Passed', 'Rollno': '009001'}

The empty curly bracket {} is used to create empty dictionary. We can also create dictionary using the built-in dict() function. Let’s understand the following example.

Example -

dict = {}  
print("Empty Dictionary is: ")  
print(dict)  
  
# Creating a Dictionary  
# using the dict() method  
dict1 = dict({1: 'Hello', 2: 'Hi', 3: 'Hey'})  
print("\nCreate Dictionary by using the dict() method : ")  
print(dict1)  
  
# Creating a Dictionary  
# with each item as a Pair  
dict2 = dict([('Devansh', 90014), ('Arun', 90015)])  
print("\nDictionary with each item as a pair: ")  
print(dict2)

Output:

Empty Dictionary is: 
{}

Create Dictionary by using the dict() method : 
{1: 'Hello', 2: 'Hi', 3: 'Hey'}

Dictionary with each item as a pair: 
{'Devansh': 90014, 'Arun': 90015}

The dictionary is mostly used to store a large amount of data where we can access any value by its key.