Python Dictionary dict Use introduction _python

The creation of a Python dictionary

Method One:

>>> blank_dict = {}
>>> product_dict = {' MAC ': 8000, ' Iphone ': 5000, ' ipad ': 4000, ' MP3 ':
>>> product_dict
{' ipad ': 4000, ' MAC ': 8000, ' Iphone ': 5000, ' mp3 ':
>>> blank_dict, Product_dict
({}, {' ipad ': 4000, ' MAC ': 8000, ' Iphone ': 5000, ' MP3 ': 300})

Method Two:
Starting with the Python 2.2 version

>>> fdict = dict ([' www ', ' www.linuxeye.com '],[' blog ', ' blog.linuxeye.com '])
>>> fdict
{ ' Blog ': ' blog.linuxeye.com ', ' www ': ' www.linuxeye.com '}

Method Three:
Starting with the Python 2.3 release, you can create a "default" dictionary with a handy built-in method Fromkeys () that has the same value for the element in the dictionary (none is default if not given):

>>> 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 dictionary check, add, delete, change

>>> product_dict = {' MAC ': 8000, ' iphone ': 5000, ' mp3 ': >>> product_dict[' iphone '] 5000 >> > product_dict[' ipad ' = 4000 #增 >>> product_dict {' ipad ': 4000, ' MAC ': 8000, ' Iphone ': 5000, ' mp3 ': "&G" T;>> Product_dict.keys () #查看索引 [' ipad ', ' MAC ', ' Iphone ', ' mp3 '] >>> product_dict.values () #查看值 [4000, 8000 , 5000,] >>> product_dict.items (' ipad ', 4000), (' MAC ', 8000), (' Iphone ', 5000), (' MP3 ',)] >>&gt ; For Product,price in Product_dict.items (): ... print product,price ... ipad 4000 MAC 8000 Iphone 5000 mp3 ; 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 ': +} >>> Product_dict.popitem () #删除第一个key和value (' ipad ', 4000) >>> product_dict {' Iphone ': 5000, ' mp3 ': >&G T;> product_dict = {' IphonE ': 5000, ' mp3 ': >>> del product_dict[' Iphone ' #用del函数删除指定key和value >>> product_dict {' mp3 ': 30 0} >>> product_dict[' mp3 ' = 299 #改 >>> product_dict {' mp3 ': 299} >>> Product_dict.clear () 
 #清空字典内容 (empty dictionary) >>> product_dict {} >>> del product_dict #删除字典 >>> product_dict = {' mp3 ': 300} >>> del product_dict #已删除报错 traceback (most recent call last): File ' <stdin> ', line 1, in &LT;MODULE&G
 T
 Nameerror:name ' product_dict ' is not defined