【python cookbook】【数据结构与算法】9.在两个字典中寻找相同点

>>> a={'x':1,'y':2,'z':3}
>>> b={'ww':10,'x':11,'y':2}
>>> a.keys()& b.keys()  #键的交集
{'y', 'x'}
>>> a.keys()- b.keys()　#键的差集
{'z'}
>>> a.keys()| b.keys()　#键的并集
{'ww', 'y', 'x', 'z'}
>>> a.items()& b.items() 
{('y', 2)}
>>> a.items()- b.items()
{('z', 3), ('x', 1)}
>>> a.items()| b.items()
{('ww', 10), ('z', 3), ('x', 1), ('x', 11), ('y', 2)}
>>> 

>>> c = {key:a[key] for key in a.keys()-{'w','z'}}  #新建一个去掉某些键的新字典
>>> c
{'y': 2, 'x': 1}
>>>