Python排序功能进阶

sorted和sort()

li = [9, 1, 8, 2, 7, 3, 6, 4, 5]

s_li = sorted(li)

print ('Sorted Variable: \t', s_li)

li.sort()

print ('Original Variable: \t', li)

输出结果：

Sorted Variable: [1, 2, 3, 4, 5, 6, 7, 8, 9]

Original Variable: [1, 2, 3, 4, 5, 6, 7, 8, 9]

如果：

li = [9, 1, 8, 2, 7, 3, 6, 4, 5]

s_li = li.sort()

print(s_li)

输出的结果是：

None

Tuple不能使用sort()，只能定义一个新的变量=sorted(a_tuple)。

class Employee():
    def __init__(self, name, age, salary):
        self.name = name
        self.age = age
        self.salary = salary

    def __repr__(self):
        return '({},{},${})'.format(self.name, self.age, self.salary)

e1 = Employee('Carl', 37, 70000)
e2 = Employee('Sarah', 29, 80000)
e3 = Employee('John', 43, 90000)

employees = [e1, e2, e3]

def e_sort(emp):
    return emp.name

s_employees = sorted(employees, key=e_sort)

print(s_employees)

或者利用lambda函数：

s_employees = sorted(employees, key=lambda e: e.name)

或者使用operator模块中的attrgetter：

s_employees = sorted(employees, key=attrgetter('age'))