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I made a Rock, Paper,Scissors game on Python. It is virtually finished, in fact you can alreay play the game with the current code. I am learning Python so I kept adding as more features as possible to practice. But I finally encountered something I could not work around. First, here is the code:

import random
player_Wins = 0
PC_Wins = 0
WinningConditions = {"paper":"rock","rock":"scissors","scissors":"paper"}

def PC():
  PC_Selection = random.choice(list(WinningConditions)) 
  print ("The PC chose " + PC_Selection + "!")
  return PC_Selection
  
def Player():
  playerSelection = input ("Let's play rock, paper, scissors! To choose your option, write rock, paper or scissors and press Enter: ") 
  if playerSelection.lower() in WinningConditions:
    print ("\nYou chose" + " " + playerSelection + "!")
    return playerSelection
  else:
    print ("\nInvalid option! You must choose rock, paper or scissors! Please try again!\n")
    Player()

def ShowScore():
    print ("Current score: \nYou have won " + str(player_Wins) + " times!\nThe PC has won " + str(PC_Wins) + " times! \n")

def QuitPlaying():
 global player_Wins
 global PC_Wins
 Quit = input("Do you want to keep playing? \nPress 'Y' and then Enter to keep playing, Press 'N' and then Enter to quit playing.\n") 
 if Quit.lower() == "y":
   return False
 elif Quit.lower() =="n":
   return True
 else:
   print ("\nInvalid option! Please enter 'Y' or 'N'!\n")
   QuitPlaying()
  
def RockPaperScissors():
  global player_Wins
  global PC_Wins
  while True:
    player_option = Player()
    PC_Option = PC()
    if player_option == PC_Option:
      print ("It's a tie!\n")
      ShowScore()
      if QuitPlaying():
        break
    elif WinningConditions[player_option] == PC_Option:
      print ("You won!\n")
      player_Wins += 1
      ShowScore()
      if QuitPlaying():
        break
    else:
     print ("The PC wins!\n")
     PC_Wins += 1
     ShowScore()
     if QuitPlaying():
        break
     
  print ("\nYou chose to quit playing.\nYou won" + " " + str(player_Wins) + " " + "times!\nThe PC won" + " " + str(PC_Wins) + " " + "times!")
  if player_Wins > PC_Wins:
      print ("You are the winner! Thanks for playing!")
  elif PC_Wins > player_Wins:
      print ("The PC is the winner! Thanks for playing!")
  elif player_Wins == PC_Wins:
      print ("Nobody won! It was a tie! Thanks for playing!")     

RockPaperScissors()

The Error happens as follows: If I intentionally input an invalid option at first, when the Player must choose their option (for the sake of testing), and then after that I try to choose a valid option ("rock", "paper", or "scissors"), it gives me this error on Line 46:

elif WinningConditions[player_option] == PC_Option:
KeyError: None

Oddly, this only happens after entering correctly "rock", "paper" or "scissors" on a second try, after having entered an invalid option intentionally on the first try. If I write a correct option on the first try, the program runs completely smoothly. Any help with this Error would be greatly appreciated!

Alex Angulo
  • 11
  • 2
  • `Player` returns `None` if you have to make a recursive call: `return Player()`. But don't use recursion for possibly infinite loops: just use a `while` loop. – chepner Jul 14 '21 at 03:24
  • I mentioned this in a comment on your [previous question](https://stackoverflow.com/q/68368162/1126841). – chepner Jul 14 '21 at 03:26
  • As a side note please try to follow PEP-8 naming conventions (e.g. lowercase method names, CamelCase class names). – Selcuk Jul 14 '21 at 03:28
  • Edit: Solved using a while loop instead of recursion on the Player() function. Thanks! – Alex Angulo Jul 14 '21 at 03:35

0 Answers0