参考：http://docs.python.org/2/library/stdtypes.html#typesmapping 

>>> a=dict(one=1,two=2,three=3)

>>> b={'one':1,'two':2,'three':3}

>>> c=dict(zip(['one','two','three'],[1,2,3]))

>>> d=dict([('two',2),('one',1),('three',3)])

>>> e=dict({'three':3,'one':1,'two':2})

>>> a==b==c==d==e

True

len(d)：d的item个数

d[key]=value 给关键字是key的item赋值

key in d: 如果key关键字在d里，返回true

clear():删除所有的items

iter(d):Return an iterator over the keys of the dictionary.  This is a shortcutfor iterkeys().

fromkeys(seq[, value]):Create a new dictionary with keys from seq and values set to value.

fromkeys() is a class method that returns a new dictionary. value defaults to None.

get(key[, default]):如果key存在的话，返回值，如果不存在，就返回空值，这个函数永远不报错keyError.

has_key(key):检测key是否存在.  has_key() isdeprecated in favor of keyind.

pop(key[, default]):如果key在dictionary里面,返回值，否则返回空值，如果关键字不存在而且没有赋空值，报错，KeyError.

其他的看网址～～吼吼～～·

例子：

>>> dishes={'eggs':2,'sausage':1,'bacon':1,'spam':500}

>>> keys=dishes.viewkeys()

>>> values=dishes.viewvalues()

>>> # iteration

>>> n=0

>>> for val in values:

        ... n+=val

>>> print(n)

504
 

>>> # keys and values are iterated over in the same order

>>> list(keys)

['eggs', 'bacon', 'sausage', 'spam']

>>> list(values)

[2, 1, 1, 500]

>>> # view objects are dynamic and reflect dict changes

>>> del dishes['eggs']

>>> del dishes['sausage']

>>> list(keys)

['spam', 'bacon']

>>> # set operations

>>> keys&{'eggs','bacon','salad'}

{'bacon'}

key|{'eggs','bacon','salad'} 返回并集

key-{'eggs','bacon','salad'}返回key有，{'eggs','bacon','salad'}没有的

key^{'eggs','bacon','salad'}返回不是key与{'eggs','bacon','salad'}都有的

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