Pull random keys from dictionary in Python that are not equal to one another

Question

So I'm trying to setup a multiple choice quiz via Python. I'm fairly new to Python, so my apologies up front if there is a simpler way to do this. However, I'm trying to really understand some basics before moving forward to newer techniques.

I have a dictionary. In this dictionary, I want to grab 3 random keys. I also want to make sure that these three keys are not equal (in other words, random from one another). Here is the code I have wrote so far:

import random

word_drills = {'class': 'Tell Python to make a new kind of thing.',
               'object': 'Two meanings: the most basic kind of thing, and any instance of some thing.',
               'instance': 'What you get when you tell Python to create a class.',
               'def': 'How you define a function inside a class.',
               'self': 'Inside the functions in a class, self is a variable for the instance/object being accessed.',
               'inheritance': 'The concept that one class can inherit traits from another class, much like you and your parents.',
               'composition': 'The concept that a class can be composed of other classes as parts, much like how a car has wheels.',
               'attribute': 'A property classes have that are from composition and are usually variables.',
               'is-a': 'A phrase to say that something inherits from another, as in a Salmon *** Fish',
               'has-a': 'A phrase to say that something is composed of other things or has a trait, as in a Salmon *** mouth.'}

key1 = ' '
key2 = ' '
key3 = ' '             

def nodupchoice():
    while key1 == key2 == key3: 
        key1 = random.choice(word_drills.keys())
        key2 = random.choice(word_drills.keys())
        key3 = random.choice(word_drills.keys())


nodupchoice()

print "Key #1: %s, Key #2: %s, Key #3: %s" % (key1, key2, key3)

I'm fairly sure the issue is with my while loop. I wanted to create a function that will keep running until all three keys are different from one another. Finally, it would print the result. Any ideas? Thanks in advance.

Answer 1

You can use random.sample:

>>> random.sample(word_drills, 3)
['has-a', 'attribute', 'instance']

and you don't need .keys(), iteration over a dictionary is over the keys.

Note that random.sample will return three unique values from the list you supply (i.e. it will never return 'has-a' twice):

>>> all(len(set(random.sample(word_drills, 3))) == 3 for i in range(10**5))
True

Answer 2

Use random.sample

>>> import random
>>> random.sample([1,2,3,4,5,6], 3)
[4, 5, 2]