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# Python Set Function

Last Updated on October 31, 2023 by Ankit Kochar

Python, a widely used programming language, provides an extensive array of built-in functions designed to enhance and simplify the coding process. Each of these built-in functions serves specific purposes, offering valuable utility in various contexts. Among these functions is "set," which is utilized to generate a set object in Python. In this article, we will delve deeply into the "set" function, examining its multitude of features, characteristics, and practical applications.

## Python Set() Function

The Python set function can be thought of as an unstructured grouping of distinct elements. It shares similarities with both lists and tuples; however, it distinguishes itself by not permitting the presence of duplicate values. In essence, each element within a set must be unique. Sets are mutable, granting you the capability to insert, delete, or alter their elements as needed.

You can create a set in Python by two methods one of them is by enclosing a comma-separated list of elements within curly braces {} and one is by putting them inside the set variable.

### Syntax of Python Set Function

The python set function has two syntaxes that are given below:

``my_set={val1, val2, val3, .......}``

or

``my_set= set(iterable)``

Note:

• We are able to include different types of numbers inside the groups.
• We must give values in the second style as iterable objects, collections, or sequences, such as lists, tuples, strings, sets, dictionaries, etc.
• An empty dictionary is made in the first syntax’s place of the empty set if the parameter is left unfilled.

### Parameters of Python Set Function

In Python, a set is created using the set() method. Python’s set function only needs one argument. It is a parameter with values that can be optionally added to the collection. A collection(set, dictionary), or iterator object should be used as the input values.

### Return Values of Python Set Function

The set() method in Python uses the iterable values passed as a parameter to build and output a set. The set() method gives an empty set if we do not pass any parameters into it.

## Examples of Python Set Function

Now, we will understand the python set function with the help of various examples.

Example 1 of Python Set Function: Creating a Set
To create a set in Python, you can use curly brackets {} or the built-in set() function. Below is the code implementation and output of the same.

Code Implementation:

```my_set = {1, 2, 3}
my_set2 = set([4, 5, 6])
print(my_set)
print(my_set2)```

Output

``````set([1, 2, 3])
set([4, 5, 6])``````

Explanation of the above code
In the above example we have created two sets by following both of the syntaxes and by printing we are getting the elements that have been inserted in the set.

Example 2 of Python Set Function: Adding Elements to a Set
To add an element to a set, you can use the add() method. The code implementation and output of the above-mentioned example are given below:

Code Implementation

```my_set = {1, 2, 3, 4}
print(my_set)```

Output

``set([1, 2, 3, 4, 5])``

Explanation of the above example
Here we have already created a set and now we have added an extra element using add function in the same set.
Note that if you try to add an element that already exists in the set, it won’t be added again.

Example 3 of Python Set Function: Removing Elements from a Set
To remove an element from a set, you can use the remove() method. The code implementation of the above-mentioned example is shown below:

Code Implementation

```my_set = {1, 2, 3}
my_set.remove(1)
print(my_set)```

Output

``set([2, 3])``

Explanation of the above code
To remove an element from an already existing set we have to pass the value of the element to be deleted like in the above example we have passed 2.
Note that if you try to remove an element that doesn’t exist in the set, you will get a KeyError.

Example 4 of Python Set Function: Union of Sets
To get the union of two sets, you can use the union() method or the "|" operator. The Code and output of the above-mentioned example are given below:

Code Implementation

```set1 = {1, 2, 3, 4}
set2 = {3, 4, 5, 6}
set3 = set1.union(set2)
set4 = set1 | set2
print(set3)
print(set4)```

Output

``````set([1, 2, 3, 4, 5, 6])
set([1, 2, 3, 4, 5, 6])``````

Explanation of the above example
In the above example, we are finding the total elements in both the sets without repetition or union by both the methods explained above.

Example 5 of Python Set Function: Intersection of Sets
To get the intersection of two sets, you can use the intersection() method or the "&" operator. The implementation and output are given below:

Code Implementation

```set1 = {1, 2, 3, 4}
set2 = {3, 4, 5, 6}
set3 = set1.intersection(set2)
set4 = set1 & set2
print(set3)
print(set4)```

Output

``````set([3, 4])
set([3, 4])``````

Explanation of the above example
In the above example, we have used two methods to find the intersections of the two sets.

Example 6 of Python Set Function: Difference of Sets
To get the difference between two sets, you can use the difference() method or the "-" operator. Below is the code and implementation of the above-mentioned example.

Code Implementation

Output

``````set([1, 2])
set([1, 2])
set([1, 2])``````

Explanation of the above code
In the above example, we are finding the difference between two sets using the above explained two methods.

## Properties of Python Set Function

Sets in Python have several properties that make them a useful data structure for various applications. Some of the properties of sets in Python are:

• Unordered: Sets in Python are unordered, which means that the elements are not stored in any particular order. This allows for efficient operations like membership testing, union, intersection, and difference.
• Unique elements: Sets in Python only contain unique elements. This makes sets useful for finding unique elements in a collection or removing duplicates.
• Immutable elements: Elements in a set must be immutable, meaning they cannot be changed once they are added to the set. This ensures that the set remains consistent and avoids potential errors due to changing elements.
• Mutable set: A set is mutable, meaning that you can add or remove elements from a set after it is created.
• Efficient operations: Sets in Python are optimized for efficient operations like membership testing, union, intersection, and difference. These operations can be performed on large sets in a matter of milliseconds, making sets a useful tool for many applications.

Conclusion
The Python set() function is a valuable tool for creating sets, which are unordered collections of unique elements. Sets in Python do not allow duplicate values, making them useful for various tasks such as eliminating duplicates from a list or testing membership in constant time. The set() function can take an optional parameter containing values to initialize the set, and it is versatile for working with different types of iterable objects.

## Frequently Asked Questions related to Python Set Function:

Here are some of the FAQs related to Python Set Function :

1. How do you create a set in Python?
You can create a set in Python using the set() function. You can pass an optional parameter containing values to initialize the set.

2. What is the purpose of the Python set() function?
The set() function in Python is used to create a set and optionally initialize it with values. It ensures that the elements in the set are unique and unordered.

3. Can you add or remove elements from a set in Python?
Yes, sets in Python are mutable, which means you can add, remove, or modify their elements using various methods like add(), remove(), and discard().

4. What happens if you try to add a duplicate element to a set?
If you attempt to add a duplicate element to a set using the add() method, it will not raise an error, but the duplicate element will be ignored since sets only allow unique values.

5. How do you check if an element exists in a set in Python?
You can check if an element exists in a set using the in operator. For example, element in my_set will return True if element is present in my_set, and False otherwise.

6. What is the difference between a set and a list in Python?
A set is an unordered collection of unique elements, while a list is an ordered collection that can contain duplicate elements. Lists use square brackets [ ], whereas sets use curly braces { } or the set() function.