## 使用operator.attrgetter() 進行對象排序

 1 from operator import attrgetter
 2 
 3 
 4 class Student:
 5     def __init__(self, name, id):
 6         self.name = name
 7         self.id = id
 8 
 9     def __repr__(self):
10         return "(%s, %s)" % (self.name, self.id)
11 
12 
13 students = [Student(‘
 
Stanley‘, 167), Student(‘Lily‘, 288), Student(‘Bob‘, 134), Student(‘Peter‘, 111)]
14 
15 students_by_id = sorted(students, key=attrgetter(‘id‘))
16 print(students_by_id)
17 # [(Peter, 111), (Bob, 134), (Stanley, 167), (Lily, 288)]
18 # 使用attrgetter速度比匿名函數更快，且同樣支持多個key，此函數同樣適用於min(), max()等函數，用法與itemgetter相同
 

19 
20 students_by_id = sorted(students, key=lambda s: s.id)
21 print(students_by_id)
22 # [(Peter, 111), (Bob, 134), (Stanley, 167), (Lily, 288)]

參考資料：
　　Python Cookbook, 3rd edition, by David Beazley and Brian K. Jones (O’Reilly).

operator.attrgetter() 進行對象排序