Set up and write your first program

Welcome to programming. By the end of this lesson you'll have written and run real Python code.

Why Python?

• It reads almost like English, so it's easy to learn.
• It's the standard for AI and data. Tools like pandas, scikit-learn, TensorFlow, PyTorch and the AI provider SDKs are all Python-first.
• It's in demand. Data analyst, ML engineer and backend developer jobs often list Python.

Google Colab: Python in your browser

Instead of installing Python, we'll use Google Colab. It's free, runs on Google's computers, and only needs a Google account and a browser.

1. Go to colab.research.google.com and sign in with your Gmail account.
2. Click New notebook.
3. You'll see a box called a code cell. Type code there.
4. Press Shift + Enter (or the play button) to run it. The output appears below.

A notebook mixes code cells and text cells. It's saved to your Google Drive automatically.

Your first program

print("Habari! I am learning Python for AI.")

Run it. print() is a function: a named command that does something. Here it displays text. Text in quotes is called a string.

Python as a calculator

print(1500 + 2000)      # addition
print(45000 - 15000)    # subtraction
print(250 * 12)         # multiplication
print(10000 / 4)        # division gives 2500.0
print(10 // 3)          # whole-number division gives 3
print(10 % 3)           # remainder gives 1
print(2 ** 10)          # power gives 1024

Anything after # is a comment. Python ignores it. Comments are notes for humans.

Errors are normal

Try running this broken code:

print("Hello)

You'll get a SyntaxError because the closing quote is missing. Every programmer sees errors all day. Read the last line of the error message: it usually tells you what's wrong and on which line. Fix it and run again.

Getting input

name = input("What is your name? ")
print("Karibu, " + name + "!")

Run it, type your name in the box, and press Enter.

Key takeaways

• Google Colab runs Python free in your browser.
• print() shows output. # starts a comment.
• Errors are normal. Read the last line, fix, and rerun.