operator.attrgetter() 进行对象排序

## 使用operator.attrgetter() 进行对象排序

 from operator import attrgetter

 class Student:
     def __init__(self, name, id):
         self.name = name
         self.id = id

     def __repr__(self):
         return "(%s, %s)" % (self.name, self.id)

 students = [Student('Stanley', 167), Student('Lily', 288), Student('Bob', 134), Student('Peter', 111)]

 students_by_id = sorted(students, key=attrgetter('id'))
 print(students_by_id)
 # [(Peter, 111), (Bob, 134), (Stanley, 167), (Lily, 288)]
 # 使用attrgetter速度比匿名函数更快，且同样支持多个key，此函数同样适用于min(), max()等函数，用法与itemgetter相同

 students_by_id = sorted(students, key=lambda s: s.id)
 print(students_by_id)
 # [(Peter, 111), (Bob, 134), (Stanley, 167), (Lily, 288)]

参考资料：
　　Python Cookbook, 3rd edition, by David Beazley and Brian K. Jones (O’Reilly).