Functions and the Standard Library

Defining Functions

def greet(name, greeting="Hi"):
    return f"{greeting}, {name}!"

print(greet("Priya"))
print(greet("Amit", "Namaste"))

Default and Keyword Arguments

def describe(title, *, author="Unknown"):
    return f"{title} by {author}"

print(describe("Python Basics", author="Groovy Grails"))

The * forces keyword-only arguments after it.

Returning Multiple Values

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

lo, hi = min_max([3, 1, 4, 1, 5])
print(lo, hi)

Lambda Functions

square = lambda x: x * x
print(square(5))

nums = [3, 1, 4, 1, 5]
nums.sort(key=lambda n: -n)   # sort descending
print(nums)

Using the Standard Library

import math
import random
import datetime

print(math.sqrt(144))            # 12.0
print(random.randint(1, 10))
print(datetime.date.today())

import os
print(os.getcwd())               # current directory

Key Points

• Functions start with def and end by returning a value.
• Default values keep function calls concise.
• math, random, datetime, os are part of the standard library.