Check If a Set Contains an Element in Python

In this tutorial, we will look at how to check if a set contains an element or not in Python with the help of some examples.

How to check if an element is in a set?

check if a python set contains an element

You can use the membership operator in to check if a set contains an element or not in Python. The following is the syntax:

# check if element e is in set a
e in a

It returns a boolean value. True if the element is present in the set and False if it isn’t.

Let’s look at an example –

# create a set
a = {1, 2, 3}
# check if 3 is in a
print(3 in a)

Output:

True

Here we check whether the element 3 is in the set a or not. We get True as the output because the set a, here, contains the element 3.

Let’s look at another example.

# create a set
a = {1, 2, 3}
# check if 4 is in a
print(4 in a)

Output:

False

Here we get False as the output because the set a does not contain the element 4.

Alternatively, you can also use the set issubset() function to check whether a set contains an element or not. The idea is to check whether the set contains a subset with the element we want to check for. Here’s an example.

# create a set
a = {1, 2, 3}
# check if 3 is in a
print({3}.issubset(a))
# check if 4 is in a
print({4}.issubset(a))

Output:

True
False

We get the correct result.

Note that you should prefer the membership operator in to using the issubset() function for checking whether a set contains an element or not as it is simple and intuitive.

How to check if an element is in a set?

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