How Can I Efficiently Remove Elements with Consecutive Duplicates, and Then Remove All Elements with Any Duplicates, from a Python List?

Identifying and Removing Duplicates from Lists in Python

Problem Statement:

The question revolves around developing a Python program that can efficiently remove elements with consecutive duplicates from a given list. The initial approach successfully eliminated consecutive duplicate elements, but it did not remove the elements containing duplicates. The desired output is a list that excludes elements with consecutive duplicates entirely.

Solution:

For the modified problem, a more elegant solution emerges using Python's powerful itertools module and the groupby() function. This group-based iteration allows us to process the list element by element, identifying consecutive duplicates.

from itertools import groupby

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

# Remove elements with consecutive duplicates
result = [key for key, _group in groupby(L)]

# Output: [1, 2, 3, 4, 5, 1, 2]

This technique simplifies the task by leveraging Python's built-in functions and eliminates the need for custom logic.

Advanced Filtering:

To further refine the filtering and exclude elements containing duplicates entirely, we can leverage the sum() function and a generator expression:

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

# Output: [2, 3, 5, 1, 2]

By iterating through each group and computing the count of elements within the group, we can exclude those with more than one occurrence.

In conclusion, the groupby() function provides a succinct and effective means for identifying and removing duplicate elements from lists. Its simplicity and efficiency make it an ideal tool for manipulating data in Python.

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