Python Sets

Sets are used to store multiple items in single variable as similar to list. But, Sets are unordered and not indexed and also has no duplicate elements.

Set Creation

Set created by declare all the items inside the curly brackets {}

#Set Creation
languages = {"Python", "Java", "Javascript"}
print(type(languages))

#Unordered and Non duplicated
languages = {"Python", "Java", "Javascript", "Java"}
print(languages)

Output

<class 'set'>
{'Javascript', 'Python', 'Java'}

It can store any immutable (int, float, string etc..) data. It cannot store any mutable (like list) data which raises exception

#Set Creation

#Mutable data type(like list) addition raises exception
user_details = {1, "PYTHON", "99.0", ["Jan", "Feb"]}
print(user_details)

Output

Traceback (most recent call last):
File "<string>", line 4, in <module>
TypeError: unhashable type: 'list'

Set Reading

Since sets are unordered and unindexed, we cannot read the element using index which raises exception

#Set Reading
languages = {"Python", "Java", "Javascript"}
print(languages[0])

Output

Traceback (most recent call last):
File "<string>", line 3, in <module>
TypeError: 'set' object is not subscriptable

We need to loop each and every element and access the set objects

#Set Reading
languages = {"Python", "Java", "Javascript"}

#Looping each element and print the same
for each in languages: print(each)

Output

Python
Javascript
Java

Set Update

In sets, we cannot update the specific element, but we can append items from another set since they are mutable in nature

#Set Update
languages = {"Python", "Java", "Javascript"}
languages[4] = "C++"

Output

Traceback (most recent call last):
File "<string>", line 3, in <module>
TypeError: 'set' object does not support item assignment

But, We can add the new set to the existing set since they are mutable in nature

#Set Update
languages = {"Python", "Java", "Javascript"}

#Adding new set to existing set
languages_new = {"C++", "R"}
languages.update(languages_new)
print(languages)

Output

{'C++', 'Java', 'Python', 'Javascript', 'R'}

Set Deletion

In sets, we can perform the specific deletion as like in list using either remove or discard function

#Set Deletion
languages = {"Python", "Java", "Javascript"}

#Remove Function
languages.remove("Java")
print(languages)

Output

{'Python', 'Javascript'}

Remove function - throws error if the element not available in the given set

#Set Deletion
languages = {"Python", "Java", "Javascript"}

#Remove method raises exception for missing key
languages.remove("C++")

Output

Traceback (most recent call last):
File "<string>", line 5, in <module>
KeyError: 'C++'

Discard function - won't throws the error if the set is not available in given set

#Set Deletion
languages = {"Python", "Java", "Javascript"}

#Discard method won't raises exception for missing key
languages.discard("C++")
print(languages)

Output

{'Java', 'Javascript', 'Python'}

Set Slicing

Since sets are unordered and unindexed, we cannot slice the set element using index

#Set slicing
languages = {"Python", "Java", "Javascript"}
print(languages[:2])

Output

Traceback (most recent call last):
File "<string>", line 3, in <module>
TypeError: 'set' object is not subscriptable

We need to loop each and every element and access the set objects

#Set slicing
languages = {"Python", "Java", "Javascript"}

#Looping each and print the element
for each in languages: print(each)

Output

Java
Python
Javascript