Remove Duplicate List Values
A set tracks membership while a result list preserves ordering.
What is Remove Duplicate List Values?
A set tracks membership while a result list preserves ordering.
Remove duplicates while preserving their first-seen order.
When should you use it?
- Learn Python syntax through a practical example.
- Build a foundation for larger programming problems.
- Test an idea quickly without a local setup.
Example code
main.py
values = [1, 2, 1, 3, 2, 4]
seen = set()
# Add each value only on its first occurrence.
unique = [value for value in values if not (value in seen or seen.add(value))]
print(unique)Expected output
[1, 2, 3, 4]How it works
Only values not already in seen are appended to the result.
Change the values and run the program in the CodeUtility online Python compiler without installing Python locally.
Practice exercises
Modify the runnable example with the exercises below to build understanding beyond copying the result.
- Change the input and predict the output before running.
- Handle empty or invalid input.
- Wrap the logic in a function and add more test cases.