Python学习笔记——字典

1.创建字典和给字典赋值，可以使用工厂方法dict()来创建字典，也可以使用fromkeys()来创建一个元素具有相同值的字典

>>> dict = {‘name‘:‘XiaoMing‘,‘age‘:20}
>>> dict
{‘age‘: 20, ‘name‘: ‘XiaoMing‘}

>>> dict2 = dict(([‘x‘,1],[‘y‘,2]))
>>> dict2
{‘y‘: 2, ‘x‘: 1}

>>> dict2 = {}.fromkeys((‘x‘,‘y‘),1)
>>> dict2
{‘y‘: 1, ‘x‘: 1

 2.访问字典中的值

>>> dict = {‘name‘:‘XiaoMing‘,‘age‘:20}
>>> dict
{‘age‘: 20, ‘name‘: ‘XiaoMing‘}
>>> for key in dict.keys():
...     print ‘key=%s,value=%s‘ % (key,dict[key])
...
key=age,value=20
key=name,value=XiaoMing

>>> for key in dict:
...     print ‘key=%s,value=%s‘ % (key,dict[key])
...
key=age,value=20
key=name,value=XiaoMing

>>> dict[‘name‘]
‘XiaoMing‘

>>> ‘name‘ in dict
True

 3.更新字典

>>> dict[‘name‘] = ‘123‘
>>> dict[‘name‘]
‘123‘

>>> del dict[‘name‘]
>>> dict
{‘age‘: 20}

>>> dict
{‘age‘: 20}
>>> dict.pop(‘age‘)
20