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Python Python Basics (2015) Letter Game App Random Item

brandonlind2
brandonlind2
7,823 Points

I dont understand the reason for the -1

Can someone explain why I'm supposed to minus one when create a random index value?

import random
# EXAMPLE
# random_item("Treehouse")
# The randomly selected number is 4.
# The return value would be "h"
def random_item(iterable):
    randomIndex= random.randint(0, len(iterable))-1
    item=iterable[randomIndex]
    return item
Nick Osborne
Nick Osborne
4,612 Points

The randomIndex should be: randomIndex = random.randint(0, len(iterable)-1) There is a chance your randomIndex could be -1. You could put randomIndex = random.randInt(1, len(iterable))-1 instead.

Because in some cases you will have IndexError. For example word 'Treehouse' has nine letters. Our range starts from 0 and if we have range 0-9, we have 10 items. And if we try get iterable[10], we've got IndexError, because we have only 9 items in iterable.