python problems with integer comparision

Question

I'm using a function in a card game, to check the value of each card, and see if it is higher than the last card played.

def Valid(card):
prev=pile[len(pile)-1]
cardValue=0
prevValue=0
if card[0]=="J":
    cardValue=11
elif card[0]=="Q":
    cardValue=12
elif card[0]=="K":
    cardValue=13
elif card[0]=="A":
    cardValue=14
else:
    cardValue=card[0]
prevValue=prev[0]
if cardValue>prevValue:
    return True
elif cardValue==prevValue:
    return True
else:
    return False

The problem is, whenever I get a facecard, it doesnt seem to work. It thinks 13>2 is True, for example

edit: sorry, I meant it thinks 13>2 is False

Answer 1

I think what you meant is that it is saying that "2" > 13 which is true. You need to change

cardValue=card[0]

to

cardValue=int(card[0])

Answer 2

Why not use a dictionary instead of a big cascade of if/else blocks?

cards = dict(zip((str(x) for x in range(1, 11)), range(1, 11)))
cards['J'] = 11
cards['Q'] = 12
cards['K'] = 13
cards['A'] = 14

then

cardValue = cards[card[0]]

Answer 3

Using a dict will make your code much cleaner:

Replace:

if card[0]=="J":
    cardValue=11
elif card[0]=="Q":
    cardValue=12
elif card[0]=="K":
    cardValue=13
elif card[0]=="A":
    cardValue=14
else:
    cardValue=card[0]

with:

cardMap = { 'J': 11, 'Q':12, 'K': 13, 'A': 14 }
cardValue = cardMap.get(card[0]) or int(card[0])