# How to Intersect Multiple Sets in Python?

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To intersect multiple sets, stored in a list `l`, use the Python one-liner `l.pop().intersection(*l)` that takes the first set from the list, calls the `intersection()` method on it, and passes the remaining sets as arguments by unpacking them from the list.

A set is a unique collection of unordered elements. The intersection operation creates a new set that consists of the elements that exist in all sets.

So, let’s dive into the formal problem formulation, shall we?

Problem: Given a list or a collection of sets. How to join those sets using the intersection operation?

Example: You’ve got a list of sets `[{1, 2, 3}, {1, 4}, {2, 3, 5}]` and you want to calculate the intersection `{1}`.

Solution: To intersect a list of sets, use the following strategy:

• Get the first element from the list as a starting point. This assumes the list has at least one element.
• Call the `intersection()` method on the first set object.
• Pass all sets as arguments into the `intersection()` method by unpacking the list with the asterisk operator `*list`.
• The result of the `intersection()` method is a new set containing all elements that are in all of the sets.

Code: Here’s the one-liner code that intersects a collection of sets.

```# Create the list of sets
lst = [{1, 2, 3}, {1, 4}, {1, 2, 3}]

# One-Liner to intersect a list of sets
print(lst[0].intersection(*lst))```

The output of this code is the intersection of the three sets `{1, 2, 3}`, `{1, 4}`, and `{2, 3, 5}`. Only one element appears in all three sets:

`{1}`

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Try it yourself: Here’s the code in an interactive code shell that runs it in your browser:

Exercise: Change the code to calculate the union of the sets in the list!

Related video: A similar problem is to perform the union operation on a list of sets. In the following video, you can watch me explain how to union multiple sets in Python:

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