Initialize a Python set

This post will discuss how to initialize a set in Python.

A set is a data structure used to store distinct values and offers fast insertion & retrieval times. There are several ways to initialize a set in Python, as discussed below:

1. Using Set constructor

The set constructor set() returns a new set initialized with elements of the specified iterable. Note that if an element is repeated in the iterable, the resultant set silently discards the duplicate.

if __name__ == '__main__':

s = set((1, 2, 3)) # create set from tuple

print(s) # { 1, 2, 3}

s = set([1, 2, 3]) # create set from list

print(s) # { 1, 2, 3}

s = set('ABC') # create set from string

print(s) # {'C', 'B', 'A'}

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If no argument is passed to the set constructor, an empty set is created.

if __name__ == '__main__':

s = set()

print(s) # set()

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2. Using Set literal syntax

You can also create a set with a comma-separated list of items placed within the curly braces {}.

if __name__ == '__main__':

s = {1, 2, 3}

print(s) # {1, 2, 3}

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Note that if no items are passed, an empty dictionary is created instead. To create an empty set, we should use the set constructor.

if __name__ == '__main__':

s = {}

print(type(s)) # <class 'dict'>

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3. Using Iterable Unpacking Operator

To create a set from a list, you can unpack items from the list inside {} syntax. This can be done using the *-operator.

if __name__ == '__main__':

x = [1, 2, 3] # list

s = {*x}

print(s) # { 1, 2, 3}

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That’s all about initializing a set in Python.

1. Using Set constructor

2. Using Set literal syntax

3. Using Iterable Unpacking Operator

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