Tutorial 11

🐍 Using Python

Let’s test that your Python installation was successful ✅ and walk through some basic exercises to get comfortable with Python syntax.

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🛠️ Activate Your Environment

Activate your Python environment created earlier (adjust the name as needed):

mamba activate default

Alternatively, you can use a Python IDE, like PyCharm 🧠 — a free educational license is available via Tel Aviv University here.

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👋 Hello, Python!

Here’s your first program:

# This program prints "Hello, World!"
print("Hello, World!")

🧾 This is how the print() function displays output.

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➕ User Input and Addition

# Get two numbers from the user
num1 = float(input("Enter the first number: "))
num2 = float(input("Enter the second number: "))

# Add the two numbers
result = num1 + num2

# Display the result
print("The sum is:", result)

🎓 input() captures user input, and float() converts it into a number.

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🔁 Even or Odd?

# Ask the user for a number
number = int(input("Enter a number: "))

# Check if the number is even or odd
if number % 2 == 0:
    print(number, "is even.")
else:
    print(number, "is odd.")

🧠 Learn about % (modulo operator) and if/else for decision-making.

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🧩 Functions in Python

Functions are reusable blocks of code that take inputs and return outputs. They help keep your code clean and modular. 🧼

🧱 Function Structure

Defined using def, and optionally use return to output a result.

Example:

# Define the function
def square(number):
    """Returns the square of a given number."""
    return number ** 2

# Call the function
result = square(5)
print("The square of 5 is:", result)

✅ Functions help you avoid repetition.

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🚗 Python Classes

A class is a blueprint for creating objects. 🧱 It bundles together data (attributes) and behaviors (methods).

🏗️ Class Structure

• Defined with class
• Constructor: __init__
• Methods: functions that operate on the object

Example: A Car 🚘

class Car:
    """A simple class to represent a car."""

    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year

    def describe(self):
        return f"{self.year} {self.make} {self.model}"

    def start(self):
        return f"The {self.make} {self.model} is now starting!"

# Create an instance
my_car = Car("Toyota", "Corolla", 2020)

# Use the methods
print(my_car.describe())
print(my_car.start())

📌 Use classes to model real-world entities and build more scalable code.

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📦 Imports & Modules

Modules allow you to reuse code across projects. Python supports:

• 🔧 Built-in modules (math, os, datetime)
• 🌐 External modules (numpy, pymatgen)
• 📁 User-defined modules (your own .py files)

Example: Import a Built-in Module

import math

number = 16
square_root = math.sqrt(number)
print(f"The square root of {number} is: {square_root}")

pi_value = math.pi
print(f"The value of pi is: {pi_value}")

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🧠 How to Import Your Own Code

Use this format to import from another file:

from path.to.file import function

If the files are in the same directory, simplify to:

from filename import function

Modular code = maintainable code 💡

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🎉 Congratulations!

You now understand the basics of:

• ✅ Running Python
• 🧮 Variables & operations
• 🔁 Loops & conditionals
• 🧩 Functions
• 🚗 Classes
• 📦 Modules

You're ready to move on to
👉 Tutorial 12 for the next step in your programming journey! 🚀