Python 字典dict使用介绍
Python字典的创建
方法一：
>>>blank_dict={}
>>>product_dict={'MAC':8000,'Iphone':5000,'ipad':4000,'mp3':300}
>>>product_dict
{'ipad':4000,'MAC':8000,'Iphone':5000,'mp3':300}
>>>blank_dict,product_dict
({},{'ipad':4000,'MAC':8000,'Iphone':5000,'mp3':300})
方法二：
从Python2.2版本开始
>>>fdict=dict((['www','www.linuxeye.com'],['blog','blog.linuxeye.com']))
>>>fdict
{'blog':'blog.linuxeye.com','www':'www.linuxeye.com'}
方法三：
从Python2.3版本开始,可以用一个很方便的内建方法fromkeys()来创建一个”默认”字典,字典中元素具有相同的值(如果没有给出，默认为None):
>>>fk_dict={}.fromkeys(('a','b'),'LinuxEye')
>>>fk_dict
{'a':'LinuxEye','b':'LinuxEye'}
>>>fk2_dict={}.fromkeys(('yeho','python'))
>>>fk2_dict
{'python':None,'yeho':None}
>>>fk3_dict={}.fromkeys('yeho','python')
>>>fk3_dict
{'y':'python','h':'python','e':'python','o':'python'}
Python字典查、增、删、改
>>>product_dict={'MAC':8000,'Iphone':5000,'mp3':300}
>>>product_dict['Iphone']
5000
>>>product_dict['ipad']=4000#增
>>>product_dict
{'ipad':4000,'MAC':8000,'Iphone':5000,'mp3':300}
>>>product_dict.keys()#查看索引
['ipad','MAC','Iphone','mp3']
>>>product_dict.values()#查看值
[4000,8000,5000,300]
>>>product_dict.items()
[('ipad',4000),('MAC',8000),('Iphone',5000),('mp3',300)]
>>>forproduct,priceinproduct_dict.items():
...printproduct,price
...
ipad4000
MAC8000
Iphone5000
mp3300
>>>product_dict.has_key('Iphone')#判断key是否存在
True
>>>product_dict.has_key('Itouch')
False
>>>product_dict.pop('MAC')#删除指定key和value
8000
>>>product_dict
{'ipad':4000,'Iphone':5000,'mp3':300}
>>>product_dict.popitem()#删除第一个key和value
('ipad',4000)
>>>product_dict
{'Iphone':5000,'mp3':300}
>>>product_dict={'Iphone':5000,'mp3':300}
>>>delproduct_dict['Iphone']#用del函数删除指定key和value
>>>product_dict
{'mp3':300}
>>>product_dict['mp3']=299#改
>>>product_dict
{'mp3':299}
>>>product_dict.clear()#清空字典内容（空字典）
>>>product_dict
{}
>>>delproduct_dict#删除字典
>>>product_dict={'mp3':300}
>>>delproduct_dict#已删除报错
Traceback(mostrecentcalllast):
File"<stdin>",line1,in<module>
NameError:name'product_dict'isnotdefined