Intersection of two arrays in Python ( Lambda expression and filter function )

Intersection of two arrays in Python ( Lambda expression and filter function )

If you want to find the intersection of two arrays using the filter() function and a lambda expression, you can do it like this:

Assume you have two lists arr1 and arr2. You can filter arr1 to keep only those elements that are also present in arr2.

Here's how you can do it:

arr1 = [1, 2, 3, 4, 5] arr2 = [4, 5, 6, 7, 8] intersection = list(filter(lambda x: x in arr2, arr1)) print(intersection) # [4, 5]

In this example:

  • The filter() function iterates through each element in arr1.
  • The lambda function returns True if the element is in arr2, and False otherwise.
  • filter() retains the elements for which the lambda function returns True.

While this method works, note that using x in arr2 for each element in arr1 can be computationally expensive for large arrays since it results in a nested loop kind of behavior. A more efficient approach for large arrays/lists would be to use sets:

intersection_set = set(arr1) & set(arr2) intersection = list(intersection_set) print(intersection)

This method takes advantage of the constant-time membership checks of sets.

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