How to Correctly Find the Intersection of Two Lists in Python?

How to Perform List Intersection in Python

When attempting to find the intersection of two lists, it is essential to understand boolean operations and the expected output.

Problem Overview:

Consider the following code snippet:

a = [1,2,3,4,5]
b = [1,3,5,6]
c = a and b
print(c)

The expected output is [1, 3, 5], but the actual output is [1, 3, 5, 6]. This is because the operation a and b performs a boolean AND, which returns true or false for each element. When both lists contain the same element, the result is true, and the element is included in the output.

Using Set Intersection for List Intersection:

To achieve a proper list intersection, we can leverage the set datatype. Sets are unordered collections of unique elements. By converting each list to a set, we eliminate duplicates and ensure that the intersection operation only considers the common elements.

The code below demonstrates this approach:

a = [1,2,3,4,5]
b = [1,3,5,6]
result = list(set(a) & set(b))
print(result)

This code snippet will produce the expected output of [1, 3, 5], as it finds the intersection of the two sets and then converts the result back to a list.

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