Tuples & Sets

Lists aren't the only way to group values in Python. A tuple is an ordered collection like a list, but locked once created; a set drops the order entirely and instead guarantees every value in it is unique.

Tuples: ordered, but unchangeable

Parentheses (or often just commas) create a tuple. It supports indexing and slicing exactly like a list, but has no .append(), .remove(), or item assignment:

point = (3, 7)
print(point[0])
print(point[1])

point[0] = 10

3
7
Traceback (most recent call last):
  ...
TypeError: 'tuple' object does not support item assignment

Reading point[0] and point[1] works exactly like a list. But a tuple is immutable — once it's created, its contents can never change in place — so the assignment on the last line crashes.

Why use a tuple instead of a list

Immutability is the point, not a limitation. A tuple is the natural choice for a fixed grouping of values that should never accidentally get edited, like a coordinate pair or a database row, and functions can return multiple values at once by packing them into one:

def min_and_max(numbers):
    return min(numbers), max(numbers)

low, high = min_and_max([4, 9, 1, 7])
print(low, high)

1 9

return min(numbers), max(numbers) packs both values into a two-item tuple automatically, and low, high = ... unpacks it straight into two separate variables in one line.

Sets: only unique values, no order

Curly braces without : pairs create a set. Adding a duplicate has no effect, and sets support the same mathematical operations you'd expect — union, intersection, difference:

tags = {"python", "code", "python", "tutorial", "code"}
print(tags)
print(len(tags))

{'python', 'code', 'tutorial'}
3

students_python = {"Amir", "Beatriz", "Chen"}
students_java = {"Chen", "Dana"}

print(students_python & students_java)
print(students_python | students_java)
print(students_python - students_java)

{'Chen'}
{'Amir', 'Beatriz', 'Chen', 'Dana'}
{'Amir', 'Beatriz'}

& is the intersection (students in both classes), | is the union (everyone, no duplicates), and - is the difference (students in the Python class but not the Java one).