gaojr

1、字典的创建

(1)通过{}和dict()创建字典

>>> a = {\'name\':\'gjr\',\'age\':32,\'job\':\'dataAnalysize\'}
>>> b = dict(name=\'gjr\',age=32,job=\'dataAnalyze\')
>>> a
{\'name\': \'gjr\', \'age\': 32, \'job\': \'dataAnalysize\'}
>>> b
{\'name\': \'gjr\', \'age\': 32, \'job\': \'dataAnalyze\'}
>>> c = dict([("name","gjr"),("age",32)])
>>> c
{\'name\': \'gjr\', \'age\': 32}
>>> d = {}
>>> e = dict()

(2)通过zip()创建字典对象

>>> k = [\'name\',\'age\',\'job\']
>>> v = [\'gjr\',32,\'teacher\']
>>> d =dict(zip(k,v))
>>> d
{\'name\': \'gjr\', \'age\': 32, \'job\': \'teacher\'}

(3)通过fromkeys创建值为空的字典

>>> a = dict.fromkeys([\'name\',\'age\',\'job\'])
>>> a
{\'name\': None, \'age\': None, \'job\': None}

 

 

2、字典的访问

(1)通过【键】访问‘值’。若键不存在,则抛出异常

>>> d
{\'name\': \'gjr\', \'age\': 32, \'job\': \'teacher\'}
>>> d[\'name\']
\'gjr\'
>>> d[\'aa\']
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
KeyError: \'aa\'

(2)通过get()方法获得‘值’。推荐使用。优点是:指定键不存在,返回None,也可以设定键不存在时默认返回的对象。

>>> d
{\'name\': \'gjr\', \'age\': 32, \'job\': \'teacher\'}

>>> d.get(\'age\')
32
>>> d.get(\'aa\',\'donot known\')
\'donot known\'

(3)列出所有的键值对

>>> d
{\'name\': \'gjr\', \'age\': 32, \'job\': \'teacher\'}

>>> d.items()
dict_items([(\'name\', \'gjr\'), (\'age\', 32), (\'job\', \'teacher\')]

(4)列出所有的键,列出所有的值

>>> d
{\'name\': \'gjr\', \'age\': 32, \'job\': \'teacher\'}

>>> d.keys()
dict_keys([\'name\', \'age\', \'job\'])
>>> d.values()
dict_values([\'gjr\', 32, \'teacher\'])

(5)len()  获得键值对的个数

(6)检测一个【键】是否在字典中

>>> d
{\'name\': \'gjr\', \'age\': 32, \'job\': \'teacher\'}

>>> \'name\' in d
True

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