Question

如何在不使用任何python-metod的情况下按字母顺序对对象列表进行排序？例如，对于具有属性Name的类Student，我尝试编写以下代码，但它不起作用：

for i in range (0, len(studentList)-1):
    if studentList[i].getName() > studentList[i+1].getName():
        aux = studentList[i].getName()
        studentList[i].getName() = studentList[i+1].getName()
        studentList[i+1].getName() = aux

Answer 1

您正在尝试分配.getName()来电的结果，这不会太好用。直接使用studentList[i]和studentList[i + 1] ;您只需要.getName()通话结果来比较学生姓名：

aux = studentList[i]
studentList[i] = studentList[i+1]
studentList[i+1] = aux

要交换列表中的两个项目，只需使用多个赋值（不需要额外的临时变量）：

studentList[i], studentList[i+1] = studentList[i+1], studentList[i]

如果不考虑排序算法，那么简单的循环当然不会产生完整的排序。

Answer 2

您要做的是使用bubblesort：

def bubble_sort(list_of_students):
    """
    Runs the bubble sort algorithm on the student class
    @rtype : list
    @param list_of_students: List of students to be sorted
    @type list_of_students: list
    """
    for _ in list_of_students:
        for j in xrange(len(list_of_students) - 1):
            if list_of_students[j] > list_of_students[j + 1]:
                list_of_students[j + 1], list_of_students[j] = list_of_students[j], list_of_students[j + 1]

    return list_of_students

尝试以下方法：

from random import randint, choice
import string


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

    def __gt__(self, other):
        if isinstance(other, Student):
            return self.name > other.name
        raise Exception("Cannot compare Student to Not-A-Student")

    def __repr__(self):
        return "{name} => {grade}".format(name=self.name, grade=self.grade)


def bubble_sort(list_of_students):
    """
    Runs the bubble sort algorithm on the student class
    @rtype : list
    @param list_of_students: List of numbers to be sorted
    @type list_of_students: list
    """
    for _ in list_of_students:
        for j in xrange(len(list_of_students) - 1):
            if list_of_students[j] > list_of_students[j + 1]:
                list_of_students[j + 1], list_of_students[j] = list_of_students[j], list_of_students[j + 1]

    return list_of_students


l = [Student(choice(string.ascii_uppercase), randint(0, 10)) for i in range(10)]
print bubble_sort(l)

如何按字母顺序排列对象列表？

2 个答案: