Python Program to remove elements that are less than K difference away in a list

Python Program to remove elements that are less than K difference away in a list

Let's say you want to remove elements from a list that have a difference of less than K from their adjacent elements.

For instance, if you have:

data = [5, 9, 11, 15, 20, 21, 30]

And you choose K = 3, the resulting list should be:

[5, 9, 15, 20, 30]

The number 11 is removed because it is only 2 units away from 9 and 4 units away from 15, but only the difference with 9 is less than K. Similarly, 21 is removed because it's 1 unit away from 20.

Steps:

  1. Iterate over the list from the second element to the second last element.
  2. Check the difference with both its preceding and succeeding neighbors.
  3. If the difference with either neighbor is less than K, mark the element for removal.
  4. Create a new list without the marked elements.

Python Code:

def remove_elements_less_than_k_difference(data, K): """ Removes elements that have a difference of less than K from their adjacent elements. :param data: List of integers. :param K: The threshold difference. :return: Modified list. """ to_remove = set() # Set to store indices of elements to remove # Check each element (except the first and last) for i in range(1, len(data) - 1): if abs(data[i] - data[i-1]) < K or abs(data[i] - data[i+1]) < K: to_remove.add(i) # Create a new list excluding the elements to remove result = [val for idx, val in enumerate(data) if idx not in to_remove] return result # Example usage: data = [5, 9, 11, 15, 20, 21, 30] K = 3 modified_data = remove_elements_less_than_k_difference(data, K) print(modified_data) # This should display [5, 9, 15, 20, 30]

Explanation:

  • We define the function remove_elements_less_than_k_difference that processes the input list.
  • We use a set to_remove to store the indices of the elements that should be removed.
  • As we iterate through the list, we check the difference between the current element and its neighbors. If the difference is less than K with any neighbor, the current element is added to the to_remove set.
  • After iterating through the list, we construct the result list using list comprehension to exclude the elements marked for removal.

This approach allows you to remove elements from a list that are too close to their neighbors based on a given threshold.

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