Python (2): List & Set

This time we'll talk about an effective combination of 3 functions in Python: [:], sorted(), set().

• [:]

  • It is usually used on a list. Assume there's a list a.

  • a[:] allows you to replace the original list a with a new list.

• sorted()

  • It sorts almost all data types in ascending order (e.g. list, tuple, set, dictionary...).

  • You can sort in descending order by adding parameter reverse=True, which is sorted(a, reverse=True).

• set()

  • It turns a list into a set.

  • It automatically remove all the duplicates in the list.

  • However, the order of the elements in the list may be unordered.

Let's see an example:

a[:] = sorted(set(a))
        return a

Assume a is a list contains [2, 3, 3 ,4, 4, 5, 5, 6, 6].

set() first turns the list into a set and remove its all duplicates.

However, set() will make the set unordered, so the set now may be {2, 4, 3, 6,5}.

sorted() then sort the set in ascending order and turn back it into a list again, so the list now is [2, 3, 4, 5, 6].

The sorted set now assigns to a[:], which allows the sorted list to replace the original list.

Return a, a now is [2, 3, 4, 5, 6].

Congratulations on completing this tutorial!

You now have the knowledge and tools to excel in this skill.

See You in Python (3)!

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