Bulls and Cows

bullsandcows.py

import random

# create 4-digit secret code
secret_code = []
avail_digits = [x for x in range(10)]
for i in range(4):
	secret_code.append(avail_digits.pop(random.randint(0,len(avail_digits)-1)))
	
#collect user input
while True:
	# get user guess
	raw_guess = input("What do you think my secret code is [Enter 4-digit number]? ")
	# validate input
	if raw_guess.isdigit() and len(raw_guess) == 4:
		break
	else:
		print("Your guess must be a 4-digit number.  Try again\n")

#stage input
guess_list, guess = ([], {})
for i in range(len(raw_guess)):
	guess_list.append(int(raw_guess[i]))
	guess[guess_list[i]] = {'bull': False, 'cow':False}

#has user figured out the secret code?
if guess_list == secret_code:
	print("You Win!")
	raise SystemExit
#no - process the guess

#check for bulls and cows
for i in range(len(secret_code)):
	if guess_list[i] == secret_code[i]:
		guess[guess_list[i]]['bull'] = True		#bull - both digit and position are correct
	elif secret_code.count(guess_list[i]):
		guess[guess_list[i]]['cow'] = True		#cow - digit is correct but not position

#accumulate bull/cow counts
cntf = lambda x: sum(1 if guess[i][x] else 0 for i in guess_list)
bullcnt = cntf('bull')
cowcnt = cntf('cow')

#display results
print("You have %i bull%s and %i cow%s" % (bullcnt, bullcnt!=1 and 's' or '', cowcnt, cowcnt!=1 and 's' or ''))