通過循環取消Python字典？

Question

我對Python非常陌生，我試圖實現的是醃製字典，然後使用某種形式的循環（道歉，如果我有術語不正確！）打印文件中的所有分數。

我使用Python 3.3.3，這裏是我的嘗試，用戶輸入一個名字和一個首先保存到文件中的分數，然後我嘗試打印它。但是我無法打印分數。

import pickle 

# store the scores in a pickled file 
def save_scores(player, score):  

    f = open("high_score.dat", "ab") 
    d = {player:score} 
    pickle.dump(d, f) 
    f.close 

# print all the scores from the file  
def print_scores(): 

    # this is the part that I can't get to work! 
    with open("high_score.dat", "r") as f: 
     try: 
      for player, score in pickle.load(f): 
       print("Player: ", player, " scored : ", score) 
     except EOFError: 
      pass  
    f.close 

def main(): 

    player_name = input("Enter a name: ") 
    player_score = input("Enter a score: ") 

    save_scores(player = player_name, score = player_score) 
    print_scores() 


main() 

input("\nPress the Enter key to exit") 

我已經Google'd和搜索爲＃1類似的問題，但我一定是使用了錯誤的術語我還沒有找到一個解決方案。

在此先感謝。

Answer 1

pickle.load(f)將返回一個字典。如果迭代字典，它會生成鍵，而不是鍵值對。

要產生鍵值巴黎，使用items()方法（如果你使用Python 2.x的使用iteritems()法）：

for player, score in pickle.load(f).items(): 
    print("Player: ", k, " scored : ", v) 

要獲得多個詞典了，你需要循環：

with open("high_score.dat", "r") as f: 
    try: 
     while True: 
      for player, score in pickle.load(f).items(): 
       # print("Player: ", k, " scored : ", v) # k, v - typo 
       print("Player: ", player, " scored : ", score) 
    except EOFError: 
     pass  

順便說一句，如果你使用with聲明，你不需要自己關閉文件。

# f.close # This line is not necessary. BTW, the function call is missing `()` 

Answer 2

pickle.load將返回你的字典（{player:score}）

驗證碼：

for player, score in pickle.load(f): 

將試圖解開返回值的元組。 另外，由於你忽略了這個異常，所以很難說出錯的地方。

Answer 3

我已經做了一些修復，使您的代碼在Python 2下工作（沒有Python 3可用，對不起）。幾處地方發生了變化。這裏有一些注意事項：

#!/bin/python2 
import pickle 

# store the scores in a pickled file 
def save_scores(player, score):  
    f = open("high_score.dat", "wb") # "wb" mode instead of "ab" since there is no obvious way to split pickled objects (surely you can make it, but it seems a bit hard subtask for such task) 
    d = {player:score} 
    pickle.dump(d, f) 
    f.close() # f.close is a method; to call it you should write f.close() 

# print all the scores from the file  
def print_scores(): 

    # this is the part that I can't get to work! 
    with open("high_score.dat", "rb") as f: # "rb" mode instead of "r" since if you write in binary mode than you should read in binary mode 
     try: 
      scores = pickle.load(f) 
      for player, score in scores.iteritems(): # Iterate through dict like this in Python 2 
       print("Player: ", player, " scored : ", score) # player instead of k and score instead of v variables 
     except EOFError: 
      pass  
    # f.close -- 1. close is a method so use f.close(); 2. No need to close file as it is already closed after exiting `where` expression. 

def main(): 

    player_name = raw_input("Enter a name: ") # raw_input instead of input - Python 2 vs 3 specific 
    player_score = raw_input("Enter a score: ") 

    save_scores(player = player_name, score = player_score) 
    print_scores() 


main() 

raw_input("\nPress the Enter key to exit")