如何更改Python字典中条目的键?


当前回答

这将小写你所有的字典键。即使你有嵌套的字典或列表。您可以执行类似的操作来应用其他转换。

def lowercase_keys(obj):
  if isinstance(obj, dict):
    obj = {key.lower(): value for key, value in obj.items()}
    for key, value in obj.items():         
      if isinstance(value, list):
        for idx, item in enumerate(value):
          value[idx] = lowercase_keys(item)
      obj[key] = lowercase_keys(value)
  return obj 
json_str = {"FOO": "BAR", "BAR": 123, "EMB_LIST": [{"FOO": "bar", "Bar": 123}, {"FOO": "bar", "Bar": 123}], "EMB_DICT": {"FOO": "BAR", "BAR": 123, "EMB_LIST": [{"FOO": "bar", "Bar": 123}, {"FOO": "bar", "Bar": 123}]}}

lowercase_keys(json_str)


Out[0]: {'foo': 'BAR',
 'bar': 123,
 'emb_list': [{'foo': 'bar', 'bar': 123}, {'foo': 'bar', 'bar': 123}],
 'emb_dict': {'foo': 'BAR',
  'bar': 123,
  'emb_list': [{'foo': 'bar', 'bar': 123}, {'foo': 'bar', 'bar': 123}]}}

其他回答

我只是要帮我妻子做一些python类的事情,所以我写了这段代码来告诉她如何做。正如标题所示,它只替换键名。这是非常罕见的,你必须替换一个键名,并保持字典的顺序完整,但我还是想分享,因为这篇文章是当你搜索它时谷歌返回的,即使它是一个非常老的线程。

代码:

dictionary = {
    "cat": "meow",
    "dog": "woof",
    "cow": "ding ding ding",
    "goat": "beh"
}


def countKeys(dictionary):
    num = 0
    for key, value in dictionary.items():
        num += 1
    return num


def keyPosition(dictionary, search):
    num = 0
    for key, value in dictionary.items():
        if key == search:
            return num
        num += 1


def replaceKey(dictionary, position, newKey):
    num = 0
    updatedDictionary = {}
    for key, value in dictionary.items():
        if num == position:
            updatedDictionary.update({newKey: value})
        else:
            updatedDictionary.update({key: value})
        num += 1
    return updatedDictionary


for x in dictionary:
    print("A", x, "goes", dictionary[x])
    numKeys = countKeys(dictionary)

print("There are", numKeys, "animals in this list.\n")
print("Woops, that's not what a cow says...")

keyPos = keyPosition(dictionary, "cow")
print("Cow is in the", keyPos, "position, lets put a fox there instead...\n")
dictionary = replaceKey(dictionary, keyPos, "fox")

for x in dictionary:
    print("A", x, "goes", dictionary[x])

输出:

A cat goes meow
A dog goes woof
A cow goes ding ding ding
A goat goes beh
There are 4 animals in this list.

Woops, that's not what a cow says...
Cow is in the 2 position, lets put a fox there instead...

A cat goes meow
A dog goes woof
A fox goes ding ding ding
A goat goes beh

这个函数获得一个字典,另一个字典指定如何重命名键;它返回一个新的字典,带有重命名的键:

def rekey(inp_dict, keys_replace):
    return {keys_replace.get(k, k): v for k, v in inp_dict.items()}

测试:

def test_rekey():
    assert rekey({'a': 1, "b": 2, "c": 3}, {"b": "beta"}) == {'a': 1, "beta": 2, "c": 3}

这将小写你所有的字典键。即使你有嵌套的字典或列表。您可以执行类似的操作来应用其他转换。

def lowercase_keys(obj):
  if isinstance(obj, dict):
    obj = {key.lower(): value for key, value in obj.items()}
    for key, value in obj.items():         
      if isinstance(value, list):
        for idx, item in enumerate(value):
          value[idx] = lowercase_keys(item)
      obj[key] = lowercase_keys(value)
  return obj 
json_str = {"FOO": "BAR", "BAR": 123, "EMB_LIST": [{"FOO": "bar", "Bar": 123}, {"FOO": "bar", "Bar": 123}], "EMB_DICT": {"FOO": "BAR", "BAR": 123, "EMB_LIST": [{"FOO": "bar", "Bar": 123}, {"FOO": "bar", "Bar": 123}]}}

lowercase_keys(json_str)


Out[0]: {'foo': 'BAR',
 'bar': 123,
 'emb_list': [{'foo': 'bar', 'bar': 123}, {'foo': 'bar', 'bar': 123}],
 'emb_dict': {'foo': 'BAR',
  'bar': 123,
  'emb_list': [{'foo': 'bar', 'bar': 123}, {'foo': 'bar', 'bar': 123}]}}

因为键是字典用来查找值的,所以实际上不能更改它们。您可以做的最接近的事情是保存与旧键相关联的值,删除它,然后使用替换键和保存的值添加一个新条目。其他几个答案说明了实现这一目标的不同方式。

我在下面写了这个函数,您可以将当前键名的名称更改为新名称。

def change_dictionary_key_name(dict_object, old_name, new_name):
    '''
    [PARAMETERS]: 
        dict_object (dict): The object of the dictionary to perform the change
        old_name (string): The original name of the key to be changed
        new_name (string): The new name of the key
    [RETURNS]:
        final_obj: The dictionary with the updated key names
    Take the dictionary and convert its keys to a list.
    Update the list with the new value and then convert the list of the new keys to 
    a new dictionary
    '''
    keys_list = list(dict_object.keys())
    for i in range(len(keys_list)):
        if (keys_list[i] == old_name):
            keys_list[i] = new_name

    final_obj = dict(zip(keys_list, list(dict_object.values()))) 
    return final_obj

假设一个JSON,你可以调用它,并通过以下行重命名它:

data = json.load(json_file)
for item in data:
    item = change_dictionary_key_name(item, old_key_name, new_key_name)

在这里可以找到从列表到字典键的转换:https://www.geeksforgeeks.org/python-ways-to-change-keys-in-dictionary/