Python zip() Function

The zip() function in Python combines two or more iterables (like lists or tuples) element by element into pairs or groups. It’s extremely useful when you want to loop through multiple sequences at once.

Syntax

zip(iterable1, iterable2, ...)

Parameters:

• iterable1, iterable2, ... – Two or more iterables (lists, tuples, strings, etc.)

Returns:

• A zip object – which is an iterator of tuples, where the i-th tuple contains the i-th element from each iterable.

Example: Zipping Two Lists

names = ["Alice", "Bob", "Charlie"]
scores = [85, 90, 95]

zipped = zip(names, scores)
print(list(zipped))

[('Alice', 85), ('Bob', 90), ('Charlie', 95)]

Example: Zipping Three Iterables

a = [1, 2, 3]
b = ['a', 'b', 'c']
c = [True, False, True]

print(list(zip(a, b, c)))

[(1, 'a', True), (2, 'b', False), (3, 'c', True)]

What If Iterables Are of Unequal Length?

When iterables passed to zip() are not of the same length, it stops at the shortest one.

x = [1, 2]
y = ['a', 'b', 'c']

print(list(zip(x, y)))

[(1, 'a'), (2, 'b')]

Use Case: Creating a Dictionary

keys = ['id', 'name', 'age']
values = [101, 'Alice', 25]

person = dict(zip(keys, values))
print(person)

{'id': 101, 'name': 'Alice', 'age': 25}

Looping with zip()

for name, score in zip(names, scores):
    print(f"{name} scored {score}")

Alice scored 85
Bob scored 90
Charlie scored 95

Unzipping Using * Operator

You can reverse a zipped object using the unpacking operator *:

pairs = [(1, 'a'), (2, 'b'), (3, 'c')]
a, b = zip(*pairs)
print(a)
print(b)

(1, 2, 3)
('a', 'b', 'c')

Common Mistakes

• Forgetting to convert the zip object to a list when printing: print(zip(...)) will just show the object type.
• Expecting zip() to handle different lengths – it doesn't pad, it truncates.

Interview Tip

zip() is frequently used in data pairing, matrix manipulation, and transforming data between structures. Be ready to combine or unzip data structures in questions.

Summary

• zip() combines multiple iterables into tuples.
• Stops when the shortest iterable is exhausted.
• Great for pairing keys and values, parallel looping, and restructuring data.

Practice Problem

Given two lists of student names and their grades, print each student with their grade using zip().

students = ["Ravi", "Meena", "Arjun"]
grades = ["A", "B", "A+"]

for student, grade in zip(students, grades):
    print(f"{student} got grade {grade}")