TypeError when assigning a random value from a list to a variable?

Question

I have a list and I want to assign a random element from that list to a new variable five times in order to generate a hand of cards. I've searched, and I can't seem to understand why my random.choice is causing errors.

import random

cards = { '2' '3' '4' '5' '6' '7' '8' '9' 'J' 'Q' 'K' 'A' }

for newCard in range(5):
        newDraw = random.choice(cards)
        playerdeck.append(newDraw)
        if newDraw in playerdeck:
                playermatches = playermatches + 1
        newDraw = oldDraw

When I try to run it I get this error:

Traceback (most recent call last):
  File "C:\Users\Nathaniel\Desktop\Fcard.py", line 6, in <module>
    newDraw = random.choice(cards)
  File "C:\Python32\lib\random.py", line 253, in choice
    return seq[i]
TypeError: 'set' object does not support indexing

Answer 1

You used { and } rather than [ and ] to define cards. Therefore, it is a set. sets are not ordered, and therefore it makes no sense to try to index into it. random.choice needs to index into a collection to pull an item out of it. Anyway, a quick fix is to replace this:

random.choice(cards)

With this:

random.choice(list(cards))

Edit: Also add commas between the elements in the set.

Answer 2

So use a list:

>>> cards = ['2', '3', '4', '5', '6', '7', '8', '9', 'J', 'Q', 'K', 'A']
>>> random.choice(cards)
'9'

Answer 3

There's a problem with your set definition. When you have multiple strings side by side, python concatenates them as if you did 'A' + 'B'. So you generated a set with only one element which is '23456789JQKA'

You don't really need a set or a list to do that:

>>> cards = '23456789JQKA'
>>> random.choice(cards)

PS: Although sets cannot be indexed, they can be iterated:

>>> [int(i) for i in {'1','2','3'}]
[1, 3, 2]

Note the order may not be preserved.