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我正在尝试制作一个程序来收集大量数据，这些数据是关于乐队中的某些玩家何时可以在今年圣诞节进行街头表演，而我正在努力让泡菜功能做我想做的事情......数据存储在下面类的类实例Player：

import pickle

class Player():
    def __init__(self, name, instrument, availability):
        self.Name=name
        self.Instrument=instrument
        self.Availability=availability

玩家PlayerList列表，起初被定义为一个空列表，我定义了一个函数，AddPlayer它将初始化一个类实例，并将玩家的详细信息存储为属性......

PlayerList=[]

def AddPlayer(PlayerList, name, instrument, availability):
    NewPlayer = Player(name, instrument, availability)
    PlayerList.append(NewPlayer)
    print("Player "+name+" has been added.\n\n")

然后，当用户退出程序时，我就有了存储玩家列表的功能......

def StartProgram(PlayerList):
    while True:
        choice=input("Would you like to:\n1 Add a Player?\n2 Quit?\n")

        if choice=="1":                
        ## Adds the details of the Player using the above function
            AddPlayer(PlayerList, "Test Player", "Instrument", ["1st Dec AM"])
            StartProgram(PlayerList)

        elif choice=="2":
            file=open("BuskingList.txt", "wb")
            file=open("BuskingList.txt", "ab")            
            def AddToList(PlayerList):
                print("PlayerList: "+str(PlayerList))
                HalfPlayerList=PlayerList[:5]
                ## For some reason, pickle doesn't like me trying to dump a list with more than
                ## 5 values in it, any reason for that?

                for Player in HalfPlayerList:
                    print("Player: "+str(Player))
                    PlayerList.remove(Player)
                    ## Each player removed from original list so it's only added once.

                print("HalfPlayerList: "+str(HalfPlayerList))
                pickle.dump(HalfPlayerList, file)
                if len(PlayerList) !=0:
                    AddToList(PlayerList)
                    ## Recursive function call while there are still players not dumped
            AddToList(PlayerList)
            file.close()
            quit()

        else:
            print("Enter the number 1, 2, or 3.\n")
            StartProgram(PlayerList)

最后在程序开始时运行该函数以加载所有玩家的信息......

def Start():
    file=open("BuskingList.txt", "rb")
    print("File contains: "+str(file.readlines()))
    PlayerList=[]
    CheckForPlayers=file.read()
    if CheckForPlayers!="":
        file=open("BuskingList.txt", "rb")
        ListOfLists=[]
        for line in file:
            ToAppend=pickle.load(file)
            ListOfLists.append(ToAppend)
        for ListOfPlayers in ListOfLists:
            for Player in ListOfPlayers:
                PlayerList.append(Player)
        StartProgram(PlayerList)


print("When entering dates, enter in the form 'XXth Month AM/PM'\n")
Start()

当程序第一次运行时（如果BuskingList.txt存在），程序运行良好，添加一个名称并腌制它并在退出时将其转储显然是可行的。但是，当程序重新启动时，它无法读取存储的数据并出现以下错误...

File contains: [b'\x80\x03]q\x00c__main__\n', b'Player\n', b'q\x01)\x81q\x02}q\x03(X\x04\x00\x00\x00Nameq\x04X\x0b\x00\x00\x00Test Playerq\x05X\n', b'\x00\x00\x00Instrumentq\x06h\x06X\x0c\x00\x00\x00Availabilityq\x07]q\x08X\n', b'\x00\x00\x001st Dec AMq\tauba.']
Traceback (most recent call last):
  File "I:/Busking/Problem.py", line 63, in <module>
    Start()
  File "I:/Busking/Problem.py", line 54, in Start
    ToAppend=pickle.load(file)
_pickle.UnpicklingError: A load persistent id instruction was encountered,
but no persistent_load function was specified.

我做了一些研究，发现这个持久的 id malarkey 应该不是问题，那么为什么会出现在这里？另外，为什么酸洗时列表上有五个值限制？任何帮助，将不胜感激。

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1 回答 1

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您首先阅读列表.readlines()：

print("File contains: "+str(file.readlines()))

然后尝试再次阅读：

CheckForPlayers=file.read()

这行不通；文件指针现在位于文件末尾。倒带或重新打开文件：

file.seek(0)  # rewind to start

并不是说您需要在此处检查文件内容；让pickle你为你做。

接下来，您逐行读取文件：

for line in file:
    ToAppend=pickle.load(file)

这不起作用；pickle 格式是二进制的，不是面向行的，您正在使用迭代读取，然后通过传入文件对象再次读取。

将文件完全留给pickle模块：

with open("BuskingList.txt", "rb") as infile:
    ToAppend=pickle.load(file)

您还在代码中提到：

## For some reason, pickle doesn't like me trying to dump a list with more than
## 5 values in it, any reason for that?

Pickle 对任何列表大小都没有问题，没有理由将您的玩家列表分成五个一组。您没有说明遇到了什么问题，但列表中的项目数量不可能是原因：

>>> import pickle
>>> with open('/tmp/test.pickle', 'wb') as testfile:
...     pickle.dump(range(1000), testfile)
... 
>>> with open('/tmp/test.pickle', 'rb') as testfile:
...     print len(pickle.load(testfile))
... 
1000

这存储并重新加载了 1000 个整数的列表。

于 2013-11-14T18:52:43.557 回答