Python: Create a list with the non-unique values filtered out

Last update on April 19 2025 13:01:09 (UTC/GMT +8 hours)

Non-Unique Values in List

Write a Python program to create a list with non-unique values filtered out.

• Use collections.Counter to get the count of each value in the list.
• Use a list comprehension to create a list containing only the unique values.

Sample Solution:

Python Code:

# Import the 'Counter' class from the 'collections' module.

from collections import Counter

# Define a function called 'filter_non_unique' that takes a list 'lst' as an argument.
def filter_non_unique(lst):
  # Create a list of items and their corresponding counts using the 'Counter' class.
  # Filter this list to include only items with a count of 1.
  return [item for item, count in Counter(lst).items() if count == 1]

# Example: Filter out non-unique elements from a list.
print(filter_non_unique([1, 2, 2, 3, 4, 4, 5]))

Sample Output:

[1, 3, 5]

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to extract only the non-unique (duplicate) values from a list while preserving their first occurrence order.
• Write a Python program to filter out non-unique values and return a list that counts how many times each duplicate appears.
• Write a Python program to create a list of elements that occur more than once in the original list, sorted in descending order.
• Write a Python program to remove unique values from a list and output only those elements that are repeated.

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