Python的dict要求key为不可变数据类型,通常采用str或int,但在某些应用场景下,需要采用自定义类型对象作key,
此时的自定义类需要实现两个特殊方法:__hash__、__eq__,用于哈希值的获取和比较
定义狗类:
class Dog():
def __init__(self,name,color):
self._n = name
self._c = color
def __hash__(self):
return hash(self._n + self._c)
def __eq__(self,other):
return (self._n,self._c)==(other._n,other._c)
定义房子:
from dog import Dog
dog_1 = Dog(name = 'mike',color = 'red')
dog_2 = Dog(name = 'tom',color = 'blue')
dog_3 = Dog(name = 'tom',color = 'blue')
#房子里有两只狗
house = {}
house[dog_1] = 1
house[dog_2] = 2
#每只狗对应的哈希值
print(hash(dog_1))
print(hash(dog_2))
print(hash(dog_3))
#输出每只狗的编号
for item in house:
print(house[item])
#名字和颜色相同的狗是同一只
print(house[dog_3]==2) >>1019109570234974571
>>5676435319618840106
>>5676435319618840106
>>1
>>2
>>True
参考:
http://www.mamicode.com/info-detail-495084.html
https://blog.csdn.net/woshiaotian/article/details/20286149