Python – Check If Set Is Empty – With Examples

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

A set is said to be empty if it does not contain any elements. You can use the following methods to check if a set is empty or not in Python.

• Comparing the length of the set with zero.
• Comparing the set with an empty set.
• Using the set in a boolean context.

Let’s now take a look at each of the above methods with the help of some examples.

The length of an empty set is zero.

You can use the Python `len()` function to calculate the length of the set and then compare it with zero to check if the set is empty or not. Here’s an example –

```# create two sets - s1 is empty and s2 is non-empty
s1 = set()
s2 = {1, 2, 3}
# check if set is empty
print(len(s1)==0)
print(len(s2)==0)```

Output:

```True
False```

We get `True` as the output for the set `s1` as it is empty and `False` for the set `s2` because it’s not empty (has non-zero length).

You can also check if a set is empty or not by comparing it with an empty set using the `==` operator. Let’s look at an example.

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```# create two sets - s1 is empty and s2 is non-empty
s1 = set()
s2 = {1, 2, 3}
# check if set is empty
print(s1 == set())
print(s2 == set())```

Output:

```True
False```

We get the same results as above.

Note that using curly braces without any elements, `{}` represents an empty dictionary and not an empty set. Thus, we’re using `set()` to represent an empty set.

If you use a set in a boolean context, it will evaluate to `True` if it has any elements and it will evaluate to `False` if the set is empty. Thus, you can use the expression `not s` to check if the set `s` is empty or not.

Here’s an example.

```# create two sets - s1 is empty and s2 is non-empty
s1 = set()
s2 = {1, 2, 3}
# check if set is empty
print(not s1)
print(not s2)```

Output:

```True
False```

We get the same result as above. `True` for the set `s1` as it’s empty and `False` for the set `s2` as it’s not empty (`s2` has three elements).

In this tutorial, we looked at three methods to check if a set is empty or not. Use the method that you are the most comfortable with. Using the `len()` function to check if a set is empty may be more explicit but it’s very intuitive and is consistent with the mathematical definition of an empty set.

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Author

• Piyush is a data professional passionate about using data to understand things better and make informed decisions. He has experience working as a Data Scientist in the consulting domain and holds an engineering degree from IIT Roorkee. His hobbies include watching cricket, reading, and working on side projects.

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