randint picks a random number. Quite often what you want is not a number at all: a random card from a deck, a random name from a class list, a random colour for the next level. If those things are already stored in a list, the random module can pick one of them for you.

Picking one item from a list

The tool is choice. Its one argument is the list to pick from:

import random

die = [1, 2, 3, 4, 5, 6]
num = random.choice(die)
print(num)

random.choice(die) picks one item from die at random, and hands it back to be stored in num. Every item in the list has the same chance of being picked.

That program is another dice roll, written a different way. randint(1, 6) picks a number from 1 to 6, and choice picks one of the six items in the list, which happen to be the numbers 1 to 6.

The list can hold anything

Where choice becomes more useful than randint is with a list of text:

import random

colours = ["red", "green", "blue", "yellow"]

colour = random.choice(colours)
print("The next level is " + colour)

Nothing in there is a number, so randint could not have done this on its own. The item that comes back is whatever was in the list: text here, so it can be joined onto other text with a + straight away, with no str() needed.

The list is not changed

choice looks at the list and picks something from it, but it does not take the item out. The list has the same items afterwards as before, which also means the same item can be picked twice in a row:

import random

colours = ["red", "green", "blue", "yellow"]

print(random.choice(colours))
print(random.choice(colours))
print(random.choice(colours))
print(colours)

Run it a few times. Sooner or later the same colour comes up twice, and the last line always prints all four.

Collecting what was picked

A picked item can be stored in a variable, and a variable can be added to a list with append, as in the previous chapter. Put that inside a for loop and the program can pick several items and keep all of them:

import random

colours = ["red", "green", "blue", "yellow"]
picked = []

for count in range(3):
    colour = random.choice(colours)
    picked.append(colour)

print(picked)

A pair of square brackets with nothing between them, [], is an empty list: a list with no items in it yet. picked starts that way, grows by one item every time round the loop, and is printed once, after the loop has finished. It has to be created before the loop: create it inside, and it is emptied again on every repetition.