How Can I Efficiently Remove Consecutive Duplicate Elements in Python?

Eliminating Consecutive Duplicate Elements in Python

In Python, the task of eliminating consecutive duplicate elements from a list can be approached in multiple ways. One approach involves iterating through the list and deleting adjacent elements with the same value. However, this method can become cumbersome when dealing with long lists.

For more efficient and elegant solutions, we can leverage Python's built-in functions and libraries. Using itertools.groupby, we can group consecutive duplicate elements and manipulate the resulting generator accordingly.

To eliminate all consecutive duplicate elements, we simply need to extract the keys from the grouped iterator.

L = [1,1,1,1,1,1,2,3,4,4,5,1,2]
from itertools import groupby
[key for key, _group in groupby(L)]

Output:

[1, 2, 3, 4, 5, 1, 2]

For the second part of the question, which requires eliminating only the elements that have consecutive duplicates, we can further filter the grouped iterator based on the number of elements in each group. Using a generator expression, we can sum the elements to determine if there's more than one element in the group.

[k for k, g in groupby(L) if sum(1 for i in g) < 2]

Output:

[2, 3, 5, 1, 2]

This technique is more Pythonic and efficient compared to the initial attempt. It leverages Python's built-in functions to group and filter the list, resulting in a concise and readable solution.

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