如何在 Python 3 中从磁盘读取和编辑列表？

Question

我有一个字典列表，我想将其附加到一个单独的磁盘文件中。然后，我希望能够读取这个字典项目列表并将它们移动到不同文件中的其他列表。

import os

# List 'x' will auto-populate itself with hundreds of new dictionary items upon run - using x.append({'name': f'{var}', 'job': f'{var2}'}) etc.

x = []

i = input('Request: ')

if i == 'add to list':
    with open('example list', 'a') as list:
        list.write(x)
elif i == 'print list':
    with open('example list', 'r') as list:
        list.read(x)
        print(list)

# in this next block, I would like to be able to move an item from the 'example list' list to a different list that is housed in a separate file

elif i == 'move item':
    # 'n' requests an integer value to represent the index in the list
    n = input('Which item do you want to move? ')
    with open('example list', 'r') as list:
        j = list[n]
        # I want to delete 'j' from 'example list' 
    with open('other list', 'a') as other_list:
        # I want to append 'j' to 'other list'
        other_list.write(j)

print('example list')

我一直在阅读和移动这些列表项。我什至不能让它以漂亮的格式打印“示例列表”。

听说过pickle模块，但是没用过。我还了解到，可能需要将这些列表保存为 json 文件，以便能够访问列表项和其中的后续字典键。

Answer 1

我认为你在这里有一个误解因为列表不会将内容转换成列表。这就像一个变量。我已经更改了您的代码的某些部分。我不知道它是否有效，因为您没有指定任何输入或输出。看看

if i == 'add to list':
    with open('example list', 'a') as f:
        # append whatever there is in 'x' into 'example list'
        f.write(x)
elif i == 'print list':
    with open('example list', 'r') as f:
        file_content=f.read()
        print(file_content)

# in this next block, I would like to be able to move an item from the 'example list' list to a different list that is housed in a separate file

elif i == 'move item':
    # 'n' requests an integer value to represent the index in the list
    n = input('Which item do you want to move? ')
    with open('example list', 'r') as f:
        # .readlines() would return a list of lines from 'example list'
        file_lines = f.readlines()
        # pop line with index 'n'
        j = file_lines.pop(n)
        # I want to delete 'j' from 'example list' 
    with open('other list', 'a') as other_list:
        # I want to append 'j' to 'other list'
        other_list.write(j)

print('example list')

Answer 2

我明白了。使用 json 模块，我能够将列表转储到外部 json 文件：

x = []

with open('json list.json', 'w') as f:
    json.dump(x, f)

然后我可以通过以下方式加载数据：

list1 = open('json list', 'r')
listread = list1.read()
data = json.loads(listread)

为了在列表之间移动项目，我使用了这个：

move_item = data[3]
del move_item
json.dumps(data)
move_to = open('other list'. 'a')
move_to.write(move_item)
list1.close()
move_to.close()

加载后，列表和其中的后续词典作为各自的对象保持不变，从而允许通过索引或键进行访问。谢谢大家，我结合了大家的建议。

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