MariasMind

Python Fundamentals

Welcome to MARIASMIND! This webpage contains some of the fundamental concepts for learning Python in a fun and easy way.

What is Python?

Python is like a magical tool for creating all sorts of amazing things, from websites and games to scientific experiments and data visualizations. It’s known for being simple and easy to read, making it perfect for beginners just starting their coding adventure.

Choosing an IDE

I recommend using Thonny for beginners because it’s super friendly and easy to use. Thonny is designed with simplicity, making it perfect for those just starting out. It provides a simple interface that won’t overwhelm you with too many options, yet it’s powerful enough to support your learning as you progress.

How to Get Started with Thonny:

  1. Go to Thonny.org and download the installer for your operating system.
  2. Run the installer and follow the instructions to install Thonny.
  3. Open Thonny.

You’ll see a clean, simple window where you can write and run your Python code.

Different Data Types

In Python, we have different types of data to work with, just like different tools in a toolbox. Here are some basics:

  • Integers (int): Whole numbers like 1, 42, or -7.
  • Floats (float): Numbers with decimals like 3.14 or -0.001.
  • Strings (str): Text wrapped in quotes like ‘Hello’ or “World”.
  • Booleans (bool): True or False values.
  • Lists: Ordered collections of items like [1, 2, ‘a’, ‘b’].
  • Dictionaries (dict): Key-value pairs like {‘name’: ‘John’, ‘age’: 30}.

Print Statements

Let’s make Python talk! The print statement lets us display text on the screen. It’s one of the most straightforward yet most powerful tools for communicating with the user.

Basic Print Statement:

print('Hello World!')

This code prints the text 'Hello World!' to the console. The print function can take multiple arguments, separated by commas, to print them together.

print('Hello', 'World!')

Practice Problem: Print a Greeting

Write a program that prints out “Good morning!” and “Welcome to Python!” on separate lines.

Using f-Strings for Formatted Output

f-Strings are a way to embed expressions inside string literals, using curly braces {}. They are a powerful tool for creating dynamic text.

name = 'Maria'
print(f'Hello, {name}!')

This code will print "Hello, Maria!" by embedding the value of the name variable inside the string.

Practice Problem: Personalized Greeting Write a program that asks for the user’s name and then prints out a personalized greeting using an f-string.

Input Statements

Now, let’s make our programs interactive! We can ask the user for input using the input function. This function displays a prompt and waits for the user to type something, which it then returns as a string.
Basic Input Statement:

name = input('What is your name? ')
print(f'Hello, {name}!')

Practice Problem: Favorite Color Write a program that asks the user for their favorite color and then prints a message that says “Your favorite color is [color].”

If , Elif, Else

Sometimes, we want our programs to make decisions. That’s where conditional statements come in. They allow your program to take different actions based on certain conditions.

Basic If Statement:

age = int(input('Enter your age: '))
if age < 18:
    print('You are a minor.')

This code checks if the user’s age is less than 18 and prints a message if the condition is true. Adding Elif and Else:

age = int(input('Enter your age: '))
if age < 18:
    print('You are a minor.')
elif age < 65:
    print('You are an adult.')
else:
    print('You are a senior.')

Practice Problem: Grade Checker Write a program that asks for a user’s grade and prints whether they have an A, B, C, D, or F based on the input. Use the following scale:

  • A: 90-100
  • B: 80-89
  • C: 70-79
  • D: 60-69
  • F: below 60

Looping

Loops help us repeat actions without writing the same code over and over. They are essential for tasks that involve repetitive actions, like processing items in a list or executing a block of code multiple times.

For Loop:

for i in range(5):
    print(i)

This code prints numbers from 0 to 4. The range function generates a sequence of numbers starting from 0 up to (but not including) the specified number.

Iterating Over a List:

fruits = ['apple', 'banana', 'cherry']
for fruit in fruits:
    print(fruit)

This code prints each fruit in the list.

Practice Problem: Print Even Numbers Write a program that prints all even numbers from 0 to 20 using a for loop.

While Loop

The while loop repeats as long as a condition is true.

count = 0
while count < 5:
    print(count)
    count += 1

This code prints numbers from 0 to 4 using a while loop. The loop continues until the condition (count < 5) is no longer true.

Practice Problem: Guess the Number Write a program that keeps asking the user to guess a number between 1 and 10 until they guess the correct number.

Breaking Out of a Loop

You can use the break statement to exit a loop early.

for i in range(10):
    if i == 5:
        break
    print(i)

This code prints numbers from 0 to 4 and then exits the loop when i equals 5

Lists

Lists are a core data structure in Python, and understanding how to manipulate them is crucial.

fruits = ['apple', 'banana', 'cherry']
print(fruits[0])  # Output: apple<br>fruits.append('date')
print(fruits)  # Output: ['apple', 'banana', 'cherry', 'date']
ruits.remove('banana')
print(fruits)  # Output: ['apple', 'cherry', 'date']

Practice Problem: Manage a To-Do List Create a program that starts with an empty list. Allow the user to add tasks to the list, view the list, and remove tasks from the list.

Functions

Functions are reusable blocks of code that perform a specific task. They help you organize your code, make it more readable, and avoid repetition.

Defining a Function:

def greet():
    print('Hello, World!')

This code defines a simple function called greet that prints a message.

Calling a Function:

greet()

This code calls the greet function.

Functions with Parameters:

def greet(name):
    print(f'Hello, {name}!')
greet('Maria')  # Output: Hello, Maria!

This code defines a function that greets a specific person by name.

Return Values:

def add(a, b):
    return a + b
result = add(3, 5)
print(result)  # Output: 8

Practice Problem: Calculate the Area of a Circle Write a function that takes the radius of a circle as a parameter and returns the area of the circle. Use the formula area = π * r^2. You can use 3.14 for π.