Tuples

Tuples

What it means

A tuple ((1, 2, 3)) is an ordered sequence like a list, but immutable — once created, you can’t add, remove, or reassign its elements. Because they’re immutable, tuples are hashable (when their contents are), so they can be used as dictionary keys or set members, unlike lists.

Examples

point = (3, 4)
x, y = point                # unpacking

coordinates = (10, 20, 30)
print(coordinates[0])       # 10
# coordinates[0] = 99       # TypeError: 'tuple' object does not support item assignment

# Common use: dict keys (tuples are hashable, lists aren't)
distances = {(0, 0): 0, (1, 1): 1.41}

def min_max(numbers):
    return (min(numbers), max(numbers))   # returning multiple values as a tuple

low, high = min_max([4, 1, 9, 2])         # unpacked directly

Common mistake

Forgetting the trailing comma when creating a single-element tuple — (5) is just the integer 5 in parentheses, not a tuple.

not_a_tuple = (5)
print(type(not_a_tuple))   # <class 'int'>

actual_tuple = (5,)        # the comma is what makes it a tuple
print(type(actual_tuple))  # <class 'tuple'>

Quick practice

1. What makes (5,) a tuple but (5) just an integer?

   Answer

   The trailing comma — parentheses alone are just grouping syntax; the comma is what actually creates a tuple.

2. Why can tuples be used as dictionary keys but lists can’t?

   Answer

   Tuples are immutable and hashable (as long as their contents are); lists are mutable and therefore unhashable, so they're not allowed as dict keys.

3. What does x, y = (3, 4) do?

   Answer

   Tuple unpacking — it assigns 3 to x and 4 to y in one statement.