Combining Everything: Functions, Conditions, and Loops

In this lesson, you'll see how to combine all the major concepts you've learned so far: functions, conditions, loops, and return values. This is where Python starts to feel powerful and expressive.

Combining Concepts

You can use loops inside functions, functions inside conditions, and even multiple functions working together.

Let’s walk through some examples:

Example 1: Filtering Even Numbers

def get_even_numbers(numbers):
    evens = []
    for number in numbers:
        if number % 2 == 0:
            evens.append(number)
    return evens

nums = [1, 2, 3, 4, 5, 6]
print(get_even_numbers(nums))  # Output: [2, 4, 6]

Example 2: Sum of Positive Numbers

def sum_positive(numbers):
    total = 0
    for n in numbers:
        if n > 0:
            total += n
    return total

print(sum_positive([-2, 5, 3, -1]))  # Output: 8

Example 3: Check if a String is a Palindrome

def is_palindrome(word):
    return word == word[::-1]

print(is_palindrome("level"))  # Output: True
print(is_palindrome("python"))  # Output: False

Mini Project Example

Let’s say we want a function that takes a list of names and returns the ones that are longer than 4 characters and start with a vowel.

def filter_names(names):
    vowels = "aeiouAEIOU"
    result = []
    for name in names:
        if len(name) > 4 and name[0] in vowels:
            result.append(name)
    return result

name_list = ["John", "Emily", "Oscar", "Uma", "Alan", "Irene"]
print(filter_names(name_list))  # Output: ['Emily', 'Oscar', 'Irene']

This example used:

A loop
An if condition
A return value
String operations

Exercise: Try It Yourself!

Write a function that returns all odd numbers from a list.
Write a function that checks if a number is prime.
Write a function that receives a list of words and returns those with more than 5 letters.
Combine loops and conditions to write a function that finds the sum of even numbers between 1 and 100.

Summary

Python becomes powerful when you combine its building blocks.
You can nest loops, conditions, and function calls to solve complex problems.
Keep your functions clean and reusable.

Python Basics

Course by zooboole,

Last Updated on 2025-02-26 16:14:49