Tuples and unpacking

Fixed groups of values

A tuple is like a list that cannot be changed. Round brackets, or often no brackets at all:

point = (3, 4)
pair = 3, 4        # the same thing
single = (3,)      # the comma is what makes it a tuple

Because they cannot change, tuples suit values that belong together and should stay that way — coordinates, RGB colours, a row from a table. They can also be dictionary keys, which lists cannot.

Unpacking pulls a tuple apart in one line:

x, y = point
name, age, city = person

The number of names has to match the number of values. This is also how you swap without a temporary variable:

a, b = b, a

Your turn: write min_max(numbers) returning the smallest and largest as a tuple. Return None for an empty list.

Returning several values

A function returning a tuple is Python's way of returning more than one thing, and the caller usually unpacks it straight away:

low, high = min_max(numbers)

Your turn: write split_name(full_name) returning (first, last). If there is only one word, the last name should be an empty string.