How to Efficiently Find the Intersection of Multiple Sets in Python?

Finding the Intersection of Multiple Sets Efficiently in Python

When working with multiple sets in Python, it is often necessary to compute their intersection, i.e., the elements that are common to all sets. A common approach is to perform a series of pairwise intersections using the set.intersection() method. However, this can be inefficient for large datasets.

Python 2.6 introduced a more efficient built-in method for computing the intersection of multiple sets. The set.intersection() method now supports multiple arguments, allowing you to specify all sets whose intersection you want to calculate.

To find the intersection of sets s1, s2, s3, and so on, simply use:

<code class="python">u = set.intersection(s1, s2, s3)</code>

If the sets are stored in a list, you can use list expansion to automate the process:

<code class="python">setlist = [s1, s2, s3]
u = set.intersection(*setlist)</code>

This notation expands the list into individual arguments when calling set.intersection() so that it can perform the intersection in a single operation.

Note that set.intersection is not a static method, meaning it must be called from an instance of the set class. If the argument list is empty, calling set.intersection() without an instance will result in an error.

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