How Can I Efficiently Remove List Elements Using Set Differences in Python?

Efficiently Removing List Elements with Set Differences

To remove elements from one list that also exist in another list, we can leverage the set comprehension feature of Python. This approach is far more efficient than naive looping methods.

Consider two lists, l1 and l2, where we want to compute l1 - l2, returning all elements in l1 that are not in l2. Using list comprehension, we can achieve this efficiently as follows:

In this code, we construct a new list, l3, by iterating over the elements of l1 using a list comprehension. For each element x in l1, we check if it exists in l2 using the not in operator. If x is not in l2, we append it to l3.

For example, if l1 = [1,2,6,8] and l2 = [2,3,5,8], l1 - l2 using this method would produce [1, 6].

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