# Creating dictionary of sets in Python

• Last Updated : 24 Oct, 2021

In this article, we will discuss how to create a dictionary of sets in Python.

## Method 1: Naive Approach

We can create a dictionary of sets by passing sets as values to the keys.

Syntax:

{ ‘Key’: Set 1, ‘Key’:Set 2,…………..,’Key’: Set n}

Example: Python program to create a dictionary of sets for student details

## Python3

 `# create  dictionary of sets for student details ` `data ``=` `{``'Student Roll-no'``: {``1``, ``2``, ``3``, ``4``, ``5``}, ` `        ``'Student Aadhar No'``: {``11``, ``22``, ``33``, ``44``, ``55``}} ` ` `  ` `  `# display ` `print``(data) `

Output:

{‘Student Roll-no’: {1, 2, 3, 4, 5}, ‘Student Aadhar No’: {33, 11, 44, 22, 55}}

As per definition, a set will not allow duplicates.

Example 2: Python program to show that it will not allow duplicates

## Python3

 `# create  dictionary of sets for student details ` `data ``=` `{``'Student Roll-no'``: {``1``, ``2``, ``3``, ``4``, ``5``, ``1``, ``2``, ``3``, ``2``}, ` `        ``'Student Aadhar No'``: {``11``, ``22``, ``33``, ``44``, ``55``, ``22``, ` `                              ``33``, ``44``, ``11``}} ` ` `  ` `  `# display ` `print``(data) `

Output:

{‘Student Roll-no’: {1, 2, 3, 4, 5}, ‘Student Aadhar No’: {33, 11, 44, 22, 55}}

## Method 2: Using defaultdict method

Here, in this approach, we are going to create a default set and then pass the key values to it.

Syntax:

defaultdict(set)

Syntax to pass the dictionary with key and value:

dictinary_name[“key”] |= {‘value1’, ‘value2′, ……………,’value n’}

where,

• dictionary_name is the input dictionary
• key is the key
• values are the set

Example: Python code to create a dictionary of sets of student data

## Python3

 `# import defaultdict module ` `from` `collections ``import` `defaultdict ` ` `  `# create an empty set of dictionary ` `dictionary ``=` `defaultdict(``set``) ` ` `  `# enter key value pair 1 ` `dictionary[``"Student Roll-no"``] |``=` `{``1``, ``2``, ``3``, ``4``, ``5``} ` ` `  `# ennter key value pair 2 ` `dictionary[``"Student Aadhar No"``] |``=` `{``11``, ``22``, ``33``, ``44``, ``55``} ` ` `  `# display ` `dictionary `

Output:

defaultdict(set,

{‘Student Aadhar No’: {11, 22, 33, 44, 55},

‘Student Roll-no’: {1, 2, 3, 4, 5}})

## Method 3: Using setdefault() method

The setdefault() method returns the value of a key in the dictionary. If not, it inserts a key with a value to the dictionary.

Syntax:

dict.setdefault(key, default_value)

where,

• key – Key to being searched in the dictionary.
• default_value is the value of a particular key

Example: Python program to insert student names set into the dictionary

## Python3

 `# Dictionary with student data ` `data ``=` `{``'Student No'``: {``1``, ``2``, ``3``, ``4``, ``5``}, ` `        ``'Student Aadhar No'``: {``11``, ``22``, ``33``, ``44``, ``55``}} ` ` `  `# using setdefault() method to get aadhar number ` `# of the students ` `print``(data.setdefault(``'Student Aadhar No'``)) ` ` `  `# using setdefault() method to get aadhar number ` `# of the students ` `print``(data.setdefault(``'Student No'``)) ` ` `  `# set the third set using setdefault method for  ` `# student names ` `data ``=` `data.setdefault( ` `    ``'Student Names'``, {``'sravan'``, ``'gopi'``, ``'ramya'``, ` `                      ``'durga'``, ``'sudheer'``}) ` ` `  `# display ` `data `

Output:

{33, 11, 44, 22, 55}

{1, 2, 3, 4, 5}

{‘durga’, ‘gopi’, ‘ramya’, ‘sravan’, ‘sudheer’}

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