NotesPythonData Structures

Tuples

Ordered but immutable — when you want a fixed collection you can't accidentally change.

A tuple looks like a list but is immutable — once created, it can't be changed, added to, or shrunk. Use one whenever a collection represents a fixed, unchanging group of values.

channel_info = ("CodeWithMunnaX", 2019, "YouTube")
print(channel_info[0])   # 'CodeWithMunnaX'
# channel_info[0] = "x"  -- TypeError: 'tuple' object does not support item assignment

Tuple unpacking

This is where tuples shine — unpacking multiple values into named variables in one line, which is exactly how a function returns "multiple values" in Python (it's really returning one tuple).

name, founded, platform = channel_info
print(name, founded, platform)

def min_max(numbers):
    return min(numbers), max(numbers)   # returns a tuple

low, high = min_max([5, 3, 8, 1, 9])
print(low, high)   # 1 9

Why prefer a tuple over a list?

  1. Intent — a tuple signals "this shouldn't change," which documents your code.
  2. Safety — you can't accidentally .append() to it or mutate it from somewhere else.
  3. Hashability — a tuple of immutable items can be used as a dict key or set element; a list can't.
locations = {
    (28.6139, 77.2090): "Delhi",
    (19.0760, 72.8777): "Mumbai",
}
print(locations[(28.6139, 77.2090)])   # 'Delhi'

A single-element tuple needs a trailing comma

not_a_tuple = (5)     # this is just the int 5
a_tuple = (5,)          # the comma makes it a tuple
print(type(not_a_tuple), type(a_tuple))
Key points to remember
  • •Tuples are ordered like lists but immutable — no append, remove, or item assignment after creation.
  • •Unpacking (a, b, c = some_tuple) is the idiomatic way to pull a tuple's values into named variables.
  • •A function 'returning multiple values' (return a, b) is really returning one tuple.
  • •Because tuples are immutable, they're hashable and can be used as dict keys or set elements — lists can't.
  • •(5) is just the int 5; (5,) — with a trailing comma — is a one-element tuple.

Unpacking and tuple-as-dict-key

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