如何向现有词典中添加关键字?它没有.add()方法。


当前回答

您可以创建一个:

class myDict(dict):

    def __init__(self):
        self = dict()

    def add(self, key, value):
        self[key] = value

## example

myd = myDict()
myd.add('apples',6)
myd.add('bananas',3)
print(myd)

给予:

>>> 
{'apples': 6, 'bananas': 3}

其他回答

在不使用add的情况下向字典中添加关键字

        # Inserting/Updating single value
        # subscript notation method
        d['mynewkey'] = 'mynewvalue' # Updates if 'a' exists, else adds 'a'
        # OR
        d.update({'mynewkey': 'mynewvalue'})
        # OR
        d.update(dict('mynewkey'='mynewvalue'))
        # OR
        d.update('mynewkey'='mynewvalue')
        print(d)  # {'key': 'value', 'mynewkey': 'mynewvalue'}
        # To add/update multiple keys simultaneously, use d.update():
        x = {3:4, 5:6, 7:8}
        d.update(x)
        print(d) # {'key': 'value', 'mynewkey': 'mynewvalue', 3: 4, 5: 6, 7: 8}
        # update operator |= now works for dictionaries:
        d |= {'c':3,'d':4}
        # Assigning new key value pair using dictionary unpacking.
        data1 = {4:6, 9:10, 17:20}
        data2 = {20:30, 32:48, 90:100}
        data3 = { 38:"value", 99:"notvalid"}
        d = {**data1, **data2, **data3}
        # The merge operator | now works for dictionaries:
        data = data1 | {'c':3,'d':4}
        # Create a dictionary from two lists
        data = dict(zip(list_with_keys, list_with_values))

我想整合有关Python字典的信息:

创建空词典

data = {}
# OR
data = dict()

使用初始值创建字典

data = {'a': 1, 'b': 2, 'c': 3}
# OR
data = dict(a=1, b=2, c=3)
# OR
data = {k: v for k, v in (('a', 1), ('b',2), ('c',3))}

插入/更新单个值

data['a'] = 1  # Updates if 'a' exists, else adds 'a'
# OR
data.update({'a': 1})
# OR
data.update(dict(a=1))
# OR
data.update(a=1)

插入/更新多个值

data.update({'c':3,'d':4})  # Updates 'c' and adds 'd'

Python 3.9+:

更新运算符|=现在适用于字典:

data |= {'c':3,'d':4}

创建合并词典而不修改原始词典

data3 = {}
data3.update(data)  # Modifies data3, not data
data3.update(data2)  # Modifies data3, not data2

Python 3.5+:

这使用了一个名为字典解包的新功能。

data = {**data1, **data2, **data3}

Python 3.9+:

合并运算符|现在适用于字典:

data = data1 | {'c':3,'d':4}

删除字典中的项目

del data[key]  # Removes specific element in a dictionary
data.pop(key)  # Removes the key & returns the value
data.clear()  # Clears entire dictionary

检查字典中是否已存在密钥

key in data

遍历字典中的成对项

for key in data: # Iterates just through the keys, ignoring the values
for key, value in d.items(): # Iterates through the pairs
for key in d.keys(): # Iterates just through key, ignoring the values
for value in d.values(): # Iterates just through value, ignoring the keys

从两个列表创建词典

data = dict(zip(list_with_keys, list_with_values))
dictionary[key] = value

如果您想在字典中添加字典,可以这样做。

示例:向字典和子字典添加新条目

dictionary = {}
dictionary["new key"] = "some new entry" # add new dictionary entry
dictionary["dictionary_within_a_dictionary"] = {} # this is required by python
dictionary["dictionary_within_a_dictionary"]["sub_dict"] = {"other" : "dictionary"}
print (dictionary)

输出:

{'new key': 'some new entry', 'dictionary_within_a_dictionary': {'sub_dict': {'other': 'dictionarly'}}}

注意:Python要求您首先添加子

dictionary["dictionary_within_a_dictionary"] = {}

在添加条目之前。

通过为字典中的键指定值,可以在字典中创建新的键/值对

d = {'key': 'value'}
print(d)  # {'key': 'value'}

d['mynewkey'] = 'mynewvalue'

print(d)  # {'key': 'value', 'mynewkey': 'mynewvalue'}

如果键不存在,则添加该键并指向该值。如果它存在,它所指向的当前值将被覆盖。