字典排序

  1. kids = [
  2.     {'name': 'xiaoming', 'score': 99, 'age': 12},
  3.     {'name': 'xiaohong', 'score': 75, 'age': 13},
  4.     {'name': 'xiaowang', 'score': 88, 'age': 15}
  5. ]
  7. # sorted
  8. sorted(kids, key=lambda x: x['score'])
  9. # 多关键字，相等就往后比较，不等或结束为止
  10. sorted(kids, key=lambda x: (x['score'], x['age']))
  12. # itemgetter
  13. from operator import itemgetter
  14. sorted(kids, key=itemgetter('score'))
  15. # 多关键字
  16. sorted(kids, key=itemgetter('score', 'age'))

对象排序

  1. class Kid:
  2.     def __init__(self, name, score, age):
  3.         self.name = name
  4.         self.score = score
  5.         self.age = age
  7.     def __repr__(self):
  8.         return 'Kid, name: {}, score: {}, age:{}'.format(self.name, self.score, self.age)
  10. from operator import attrgetter
  11. kids = [Kid('xiaoming', 99, 12), Kid('xiaohong', 75, 13), Kid('xiaowang', 88, 15)]
  12. sorted(kids, key=attrgetter('score'))
  13. # 使用lambda来实现
  14. sorted(kids, key=lambda x: x.score)

自定义排序

我们可以在sorted函数的参数当中传入reverse=True来控制是正序还是倒叙，但是如果我使用多关键字，想要按照某个关键字升序，某个关键字降序怎么办

  1. # 先实现自定义元素大小的函数
  2. def cmp(kid1, kid2):
  3.     return kid1.age < kid2.age if kid1.score == kid2.score else kid1.score > kid2.score
  5. # 将函数重载为比较类并比较
  6. from functools import cmp_to_key
  7. sorted(kids, key=cmp_to_key(cmp))
  9. # 也可以直接在kid类中重载比较函数，然后直接调用sorted，不用任何其他传参就可以对它进行排序了
  10. class Kid:
  11.     def __init__(self, name, score, age):
  12.         self.name = name
  13.         self.score = score
  14.         self.age = age
  16.     def __repr__(self):
  17.         return 'Kid, name: {}, score: {}, age:{}'.format(self.name, self.score, self.age)
  19.     def __lt__(self, other):
  20.         return self.score > other.score or (self.score == other.score and self.age < other.age)