I am getting an incorrect average, and not sure why? What's wrong with my code?

[deanhystad]

Your big error is in oneGame()

def oneGame(initial):
    countFlips = 0
    bankroll = initial
    while 0 < bankroll < 2*initial:
        # This is where you error was.  You did multiple
        # adds and subtracts for each hand.  There should
        # only be 1 ad or subtract
        for card in shuffledDeck[0:6]:  # Look at top six cards
            if 'ace' in card:
                bankroll += 1
                break # Stop after find first ace
        else: 
            bankroll -= 1 # Only do this if for loop completes              
        countFlips += 1
    return countFlips

Your code added a dollar for each ace and subtracted a dollar for each non-ace. If you drew 4 aces you would add $2, but if you drew no aces you lost $6. In the code above we break out of the for loop after finding the first ace. The "else" statement is only executed when there are no aces in the hand.

The for/else is a bit confusing. I don't think any other programming language has this logic construct. You might find the code easier to understand if the "hand" logic is broken out into it's own function.

def hand():
    for card in shuffledDeck[0:6]:  # Look at top 6 cards
        if 'ace' in card:
            return 1  # Return 1 if we find an ace
    return -1  # Return -1 if no ace found          

def oneGame(initial):
    countFlips = 0
    bankroll = initial
    while 0 < bankroll < 2*initial:
        bankroll += hand()
        countFlips += 1
    return countFlips