从文件中读取字典，修改，然后写入新文件。 Python

Question

我正在做一项学校作业，要求我：

1. 将我之前创建的字典作为字符串写入文件。
2. 然后将该字典再次导入 python 并反转它
3. 将倒排字典写入新文件。

我遇到了一些问题...

write2file 函数工作正常，并使用字典创建一个文本文件。但是当需要将其拉回并反转数据时，我收到一个类型错误，抱怨字符串索引必须是整数。我迷路了。任何帮助理解将不胜感激。

我是 python 新手。请温柔 :) 提前感谢您帮助我了解我做错了什么。

<pre><code> 

import os

ChessPlayerProfile = {
    "Matt": [("Rating: ", 2200), ("FIDE ID: 0147632DF"), ("Member Status: ", True)],
    "Will": [("Rating: ", 2200), ("FIDE ID: 3650298MK"), ("Member Status: ", False)],
    "Jithu": [("Rating: ", 1900), ("FIDE ID: 5957200LH"), ("Member Status: ", True)],
    "Lisa": [("Rating: ", 2300), ("FIDE ID: 7719328CX"), ("Member Status: ", False)],
    "Nelson": [("Rating: ", 2500), ("FIDE ID: 6499012XX"), ("Member Status: ", True)],
    "Miles": [("Rating: ", 1600), ("FIDE ID: 4392251TJ"), ("Member Status: ", True)],
}


def write2file():
    with open("chessdict.txt", "w") as f:  # Open file using context manager for memory safety
        f.write(str(ChessPlayerProfile))   # dumping dict to file
                                           # (wanted to use pickle but we need strings per instructions)


def Read_Invert_Write():
    with open("chessdict.txt", "r") as f:       # Read File 1
        TempContent = f.read()                  # assign to temp variable
        invert(TempContent)                     # Invert contents of temp variable
        with open("new_dict.txt", "w") as f:    # create File 2
            f.write(str(TempContent))           # and write new dict from variable contents


def invert(d):                             # Previous function for inverting the dict
    inverse = dict()
    for key in d:                          # Iterate through the list that is saved in dict
        val = d[key]
        for item in val:                   # Check if in the inverted dict the key exists
            if item not in inverse:
                inverse[item] = [key]      # If not then create a new list
            else:
                inverse[item].append(key)
    return inverse


def main():
    write2file()
    Read_Invert_Write()
main()

    </pre></code>

输出：

    Traceback (most recent call last):
      File "/home/vigz/PycharmProjects/pythonProject/copytest.py", line 44, in 
        main()
      File "/home/vigz/PycharmProjects/pythonProject/copytest.py", line 43, in main
        Read_Invert_Write()
      File "/home/vigz/PycharmProjects/pythonProject/copytest.py", line 15, in Read_Invert_Write
        invert(TempContent)
      File "/home/vigz/PycharmProjects/pythonProject/copytest.py", line 32, in invert
        val = d[key]
    TypeError: string indices must be integers

Answer 1

给定一个文件 f 像你一样创建：

with open("chessdict.txt", "r") as f:

f.read() 的结果是 str，而不是 dict。结果，当你调用invert(f.read())时，这个：

for d in key:
    val = key[d]

本质上是遍历f.read() 中的字符 并尝试获取f.read()[character]（这不是一个有效的操作）。具体来说，如果chessdict.txt的内容是：

{"foo": "bar"}

invert(f.read())中的迭代：

inverse = dict()
for key in d:

执行为：

inverse = dict()
for key in '{"foo": "bar"}':  # Returns '{', '"', 'f', ...

如果chessdict.txt包含JSON编码的字符串，你可以试试：

import json

with open("chessdict.txt", "r") as f:
    invert(json.load(f))

如果f 的内容可以解组为 JSON，则将返回dict。此时，您不妨重写invert，使其遍历键和值：

def invert(d):
    inverse = dict()
    for key, value in d.items():
        for item in val:
            ...

当需要将字典写入到文件时，你应该避免str(your_dictionary)：如果你想把它变成一个JSON编码的字符串，你应该写：

with open(your_output_file, "w+") as f:
    json.dump(your_dict, f).

这将正确地将其编组为 JSON 格式（避免将 {\"foo\": ...} 等转义字符串写入文件时出现问题）。