max()

max() Signatures

max(iterable, *, key=None)
max(iterable, *, default, key=None)
max(arg1, arg2, *args, key=None)

max() Examples

With a list of numeric values as an argument:

>>> max([3.4, 5, 9, 1.2, -5])
9

With a string as an argument:

>>> max("abcdefghijklmnopqrstuvwxyz")
'z'

With multiple string arguments:

>>> max("banana", "apple", "cherry")
'cherry'

max() Common Use Cases

The most common use cases for the max() functions include:

• Finding the largest numbers in a series of numbers.
• Identifying the latest strings alphabetically.
• Extracting the maximum values from dictionary keys or values.
• Clipping values to a specified range in data processing.

max() Real-World Example

Suppose you have a dictionary of product prices and want to identify the most expensive product. You can use max() with the .items() method and a lambda function as the key argument:

>>> prices = {
...    "banana": 1.20,
...    "pineapple": 0.89,
...    "apple": 1.57,
...    "grape": 2.45,
... }

>>> max(prices.items(), key=lambda item: item[1])
('grape', 2.45)

This example demonstrates how max() can help you identify the most expensive products by using the dictionary’s values for comparison.

max() in Custom Classes

You can support max() in custom classes by implementing the .__gt__() special methods. Here’s a quick example:

from datetime import date

class Person:
    def __init__(self, name, birth_date):
        self.name = name
        self.birth_date = date.fromisoformat(birth_date)

    def __repr__(self):
        return (
            f"{type(self).__name__}"
            f"({self.name}, {self.birth_date.isoformat()})"
        )

    def __gt__(self, other):
        return self.birth_date < other.birth_date

# Usage
jane = Person("Jane Doe", "2004-08-15")
john = Person("John Doe", "2001-02-07")
print(max(jane, john))  # Output: Person(John Doe, 2001-02-07)

This implementation allows you to use max() on instances of the Person class, comparing them by birthdate.