通过循环解开 Python 字典？

Question

我对 Python 非常陌生，我想要实现的是腌制字典，然后使用某种形式的循环（如果我的术语不正确，请道歉！）打印文件中的所有分数。

我正在使用 Python 3.3.3，这是我的尝试，用户输入一个名称和一个分数，它首先保存到一个文件中，然后我尝试打印它。但是我无法打印分数。

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")   

我在 Google 上搜索过类似问题的 Stackoverflow，但我必须使用错误的术语，因为我还没有找到解决方案。

提前致谢。

Answer 1

pickle.load(f) 将返回一个字典。如果你迭代字典，它会产生键，而不是键值对。

要生成 key-value paris，请使用 items() 方法（如果您使用 Python 2.x，请使用 iteritems() 方法）：

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

要取出多个字典，您需要循环：

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    

顺便说一句，如果你使用with 语句，你不需要自己关闭文件。

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

Answer 2

pickle.load 将返回您的字典 ({player:score})

这段代码：

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

将尝试将返回的值解压缩为一个元组。 此外，由于您忽略了异常，因此很难判断出了什么问题。

Answer 3

我已经做了一些修复以使您的代码在 Python 2 下工作（抱歉，没有可用的 Python 3）。几个地方都变了。这里有一些注释：

#!/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")