Tuples and Sets in Python — When to Use Each

Python has four built-in collections. You know lists; this lesson covers tuples and sets, and compares all four.

Part A — Tuples

A tuple is like a list that cannot change (immutable). Use round brackets.

point = (3, 4)
print(point[0], len(point))
rgb = 255, 128, 0          # brackets are optional
print(type(rgb))
single = (5,)              # one item needs a comma
print(type(single), type((5)))

3 2
<class 'tuple'>
<class 'tuple'> <class 'int'>

Why use tuples?

• To store values that shouldn't change (coordinates, date parts, RGB colours).
• Tuples can be dictionary keys and set items; lists can't.
• Functions return several values as a tuple.

Unpacking

def min_max(nums):
    return min(nums), max(nums)

low, high = min_max([7, 2, 9, 4])
print(low, high)

first, *rest = [10, 20, 30, 40]
print(first, rest)

2 9
10 [20, 30, 40]

Part B — Sets

A set keeps only unique items and has no order. It's very fast at checking x in s.

nums = [3, 1, 3, 2, 1, 3]
unique = set(nums)
print(len(unique), sorted(unique))

skills = {"python", "sql"}
skills.add("git")
skills.add("python")        # already there — no duplicate
skills.discard("java")      # no error if missing
print(sorted(skills))

3 [1, 2, 3]
['git', 'python', 'sql']

An empty set is set(), not {} — that's an empty dictionary.

Set operations (like Venn diagrams)

python_students = {"Asha", "Ravi", "Neha"}
java_students = {"Ravi", "Kabir", "Neha"}

print(sorted(python_students | java_students))   # union: in either
print(sorted(python_students & java_students))   # intersection: in both
print(sorted(python_students - java_students))   # difference: only Python
print(sorted(python_students ^ java_students))   # in exactly one

['Asha', 'Kabir', 'Neha', 'Ravi']
['Neha', 'Ravi']
['Asha']
['Asha', 'Kabir']

Which one should I use?

Common mistakes

• (5) is just the number 5; a one-item tuple needs a comma: (5,).
• Using {} to make an empty set (it makes a dict).
• Expecting a set to keep insertion order or allow indexing (s[0] is an error).

Quick recap

• Tuple: ordered, immutable, ( ); great for fixed data and returning many values.
• Set: unique, unordered, { }; add, discard, |, &, -, ^.
• set() for an empty set.