Which is more efficient in Python: a Python set vs list? If order is not important and I will be checking for duplicates anyway, is a Python set slower than a Python list?
Hello @anjuyadav.1398
Hope you are doing great! Here is the answer to your question!
Use a Python Set for Faster Duplicate Checking: If you’re primarily concerned with checking duplicates, a Python set is much more efficient. Sets are implemented as hash tables, so membership checks (i.e., checking if an item exists) are generally O(1) on average. In contrast, for a Python list, membership checks are O(n), meaning that as the list grows larger, the time it takes to check for duplicates increases significantly.
Well described, @macy-davis! I’d just like to add that if maintaining the order of elements is a priority, a Python set might not be the ideal solution since sets don’t retain order. In such cases, you could stick to a Python list. While lists don’t ensure uniqueness, you can manually check for duplicates using a loop or comprehension. Of course, this approach is slower, but it works well when order retention is critical.
Hey @anjuyadav.1398
Both of you make excellent points!
In fact, if you need to balance both worlds—efficient duplicate checking and maintaining order—you can combine a Python set with a Python list. For example, use the list to keep the ordered sequence and the set to track uniqueness. Each time you add a new element, check the set first. If it’s not there, add the element to both the list and the set. This way, you get order retention and efficiency!