Python: Create a list with the unique values filtered out

Last update on April 19 2025 12:58:00 (UTC/GMT +8 hours)

Unique Values in List

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

Sample Solution:

Python Code:

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

# Define a function called 'filter_unique' that takes a list 'lst' as an argument.
def filter_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 greater than 1.
  return [item for item, count in Counter(lst).items() if count > 1]

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

Sample Output:

[2, 4]

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to extract only the unique values from a list, preserving the order of their first occurrence.
Write a Python program to identify unique values in a list and then sort them in ascending order.
Write a Python program to remove duplicate values from a list while maintaining the original order.
Write a Python program to create a list of unique values from a nested list of numbers.

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