#按照list的第二键值排序 disP2P = [[1,2,3],[2,3,4],[4,5,6]]

 disP2P = sorted(disP2P,key = lambda x:x[2])

 student_tuples = [

         ('john', 'A', 15),

         ('jane', 'B', 12),

         ('dave', 'B', 10),

 ]

 sorted(student_tuples, key=lambda student: student[2])   # sort by age

 [('dave', 'B', 10), ('jane', 'B', 12), ('john', 'A', 15)]

  class Student:

         def __init__(self, name, grade, age):

                 self.name = name

                 self.grade = grade

                 self.age = age

         def __repr__(self):

                 return repr((self.name, self.grade, self.age))

 student_objects = [

         Student('john', 'A', 15),

         Student('jane', 'B', 12),

         Student('dave', 'B', 10),

 ]

 >>> sorted(student_objects, key=lambda student: student.age)   # sort by age

 #[('dave', 'B', 10), ('jane', 'B', 12), ('john', 'A', 15)]

 sorted(d.items(),key = lambda x:x[1],reverse = True)

 #变成元组list的形式，然后对list排序再恢复回来

 tmlist = []

         for l in range(n):

             tmlist = tmlist + [(X[l][i],y[l],w[l])]

         tmlist =sorted(tmlist,key = lambda x: x[0])

         XX = []

         W = []

         Y = []

         for l in range(n):

             XX = XX+[tmlist[l][0]]

             Y = Y + [tmlist[l][1]]

             W = W + [tmlist[l][2]]