字典简介

字典是键值存储的示例，也称为 Python 中的映射。它允许你通过引用键来存储和检索元素。由于字典是由密钥引用的，因此它们具有非常快速的查找。由于它们主要用于按键引用项目，因此它们不会被排序。

创造一个字典

字典可以通过多种方式启动：

文字语法

d = {}                        # empty dict
d = {'key': 'value'}          # dict with initial values

Python 3.x >= 3.5

# Also unpacking one or multiple dictionaries with the literal syntax is possible

# makes a shallow copy of otherdict
d = {**otherdict}
# also updates the shallow copy with the contents of the yetanotherdict.
d = {**otherdict, **yetanotherdict}

dict 理解

d = {k:v for k,v in [('key', 'value',)]}

另见： 理解

内置类：dict()

d = dict()                    # emtpy dict
d = dict(key='value')         # explicit keyword arguments
d = dict([('key', 'value')])  # passing in a list of key/value pairs
# make a shallow copy of another dict (only possible if keys are only strings!)
d = dict(**otherdict)         

修改字典

要将项添加到字典，只需创建一个带有值的新键：

d['newkey'] = 42

也可以添加 list 和 dictionary 作为值：

d['new_list'] = [1, 2, 3]
d['new_dict'] = {'nested_dict': 1}

要删除项目，请从字典中删除密钥：

del d['newkey']