How do the built-in map, filter, and zip functions work?

map — applies a function to each item:

numbers = [1, 2, 3, 4, 5]
squares = list(map(lambda x: x ** 2, numbers))
# [1, 4, 9, 16, 25]

# Equivalent using comprehension
squares = [x ** 2 for x in numbers]

filter — selects items by condition:

numbers = [1, 2, 3, 4, 5, 6]
evens = list(filter(lambda x: x % 2 == 0, numbers))
# [2, 4, 6]

# Equivalent using comprehension
evens = [x for x in numbers if x % 2 == 0]

zip — combines multiple collections:

names = ["Anna", "Boris", "Vera"]
ages = [25, 30, 22]

pairs = list(zip(names, ages))
# [('Anna', 25), ('Boris', 30), ('Vera', 22)]

# Often used to create a dictionary
user_ages = dict(zip(names, ages))
# {'Anna': 25, 'Boris': 30, 'Vera': 22}

Features:

• All three functions return iterators, not lists — you need to wrap them in list() to get a list.
• zip stops according to the shortest collection.
• In most cases, list comprehension is considered a more readable alternative to map and filter.