Let Python roll the dice

The problem...

Every program you've written so far is predictable. Same input — same output. Every time.

But real programs aren't always like that. Games. Simulations. Security. Testing. All of them need values you didn't choose.

You need Python to surprise you.

The idea!

Python has a built-in module called random. It generates values you can't predict — numbers, choices, outcomes. You set the boundaries. Python picks.

Importing random

import random

One line at the top of your file. That's all. import loads a module — a collection of ready-made tools. You'll learn more about modules in the Functions chapter. For now — just write it and move on.

randint() — a random integer

import random

number = random.randint(1, 10)
print(number)    # different every time

randint(1, 10) gives you a random integer between 1 and 10. Both ends included. Run it ten times — ten different results.

Simulating a dice roll

import random

roll = random.randint(1, 6)
print(f"You rolled: {roll}")

Six possible outcomes. Python picks one. You don't control which.

choice() — pick from a sequence

import random

word = "Bull"
letter = random.choice(word)
print(f"Random letter: {letter}")

choice() picks one item from a sequence at random. A string, a range — anything Python can move through.

Using random with what you know

import random

for i in range(5):
    roll = random.randint(1, 6)
    print(f"Roll {i + 1}: {roll}")

# Roll 1: 4
# Roll 2: 1
# Roll 3: 6
# Roll 4: 2
# Roll 5: 5

Five rolls. Five different results. The loop is predictable — the values inside it aren't.

Heads up!

• import random goes at the top of your file — always
• randint(a, b) — both a and b are included
• choice(sequence) — picks one item at random
• Every run gives different results — that's the point

The mindset shift

Stop thinking: "I control every value."

Start thinking: "I control the boundaries. Python fills in the surprise."

What you should understand now

• import random loads the random module
• random.randint(a, b) — random integer, both ends included
• random.choice(sequence) — random item from a sequence
• Random values make programs unpredictable — and useful