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random: make things surprising

Computers usually do the exact same thing every time. The random module breaks that — it lets your code roll dice, pick surprises, and scatter things all over.

The big idea

The random module gives your code surprises — like a random number, or a random pick from a list.

See it in code

1Start simple

The plainest surprise is a random number. random.randint(1, 6) rolls a number between 1 and 6, like a dice. We call random.seed(5) first so you get the same rolls we did:

python
import random

random.seed(5)
print("A random number 1-6:", random.randint(1, 6))
print("Another:", random.randint(1, 6))
Run it — two dice rolls from the random module:
A random number 1-6: 5
Another: 3

Two rolls, two surprises. The seed makes them repeatable — without it, you'd get different numbers every run.

2A step further

random can also pick from a list for you. random.choice(colors) grabs a surprise item, so a loop can hand each star its own color:

python
import random

random.seed(5)
colors = ["red", "blue", "green", "yellow"]
for i in range(4):
    print("star", i, "->", random.choice(colors))
Run it — a surprise color for each star:
star 0 -> green
star 1 -> green
star 2 -> red
star 3 -> yellow

Sometimes the same color comes up twice in a row — that's real randomness, not a bug! This is exactly how we'll pick each star's color on the canvas.

3In our world

Now paint a starfield where no two stars are alike. random.randint(40, 460) picks a surprise spot for each star, and random.choice(PALETTE) grabs a surprise color — with a seed up front so the same sky shows up every run:

python
import random
from art import Canvas, PALETTE, star

screen = Canvas.create()
Canvas.fill(screen)

random.seed(5)
for i in range(20):
    x = random.randint(40, 460)
    y = random.randint(40, 460)
    star(screen, x, y, size=30, color=random.choice(PALETTE))
Run it — twenty stars scattered in surprise spots and colors:
Twenty small stars in mixed colors scattered all across a dark navy canvas.

randint gives each star a random spot and choice a random color — the same two tools from the warm-ups — so the starfield looks natural instead of neat. Remove the seed line and you'd get a brand-new sky each run.

The same idea, everywhere

Randomness makes things feel alive. Games roll dice and shuffle cards. Art scatters shapes. Quizzes pick a surprise question. Any time you want a surprise instead of the same thing, reach for random.

Try it yourself

Change range(20) to range(60) for a thicker starfield. Then change the seed number from 5 to 9 and watch a totally different sky appear.

The common mistake

Forgetting to import random. The random tools live in a module, so random.randint(...) only works after you write import random at the top. Miss it, and Python won't know what random means.

What it unlocks

Randomness builds on imports and powers generative art and randomness in art.

Older, or want more depth? Read the Teens version →

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