Python中的list.sort()方法和函数sorted(list)

In [90]: x = [4, 6, 2, 1, 7, 9]

In [91]: x.sort()

In [92]: x
Out[92]: [1, 2, 4, 6, 7, 9]
In [98]: aa = x.sort()
In [99]: aa #  返回None

In [94]: a = sorted(x)
In [95]: a
Out[95]: [1, 2, 4, 6, 7, 9]

In [96]: x
Out[96]: [4, 6, 2, 1, 7, 9]

## 1、key在使用时必须提供一个排序过程总调用的函数：
x = ['mmm', 'mm', 'mm', 'm']
x.sort(key=len)
print(x)  # 输出 ['m', 'mm', 'mm', 'mmm']

## 2、reverse实现降序排序，需要提供一个布尔值：
y = [3, 2, 8, 0, 1]
y.sort(reverse=True)
print(y)  # [8, 3, 2, 1, 0]

## 1、key在使用时必须提供一个排序过程总调用的函数：
x = ['mmm', 'mm', 'mm', 'm']
x.sort(key=len)
print(x)  # 输出 ['m', 'mm', 'mm', 'mmm']

## 2、reverse实现降序排序，需要提供一个布尔值：
y = [3, 2, 8, 0, 1]
y.sort(reverse=True)
print(y)  # [8, 3, 2, 1, 0]

def sort_priority2(values,group):
    found = False
    def helper(x):
        if x in group:
            found = True
            return (0,x)
        return (1,x)
    values.sort(key=helper)
    return found
numbers = [8,3,1,2,5,4,7,6]
group = [8,5,2,3,4,7,9]
found = sort_priority2(numbers,group)
print('最后的numbers',numbers)
print("found",found)
输出:最后的numbers [2, 3, 4, 5, 7, 8, 1, 6]
found False

def sort_priority2(values,group):
    found = False
    def helper(x):
        if x in group:
            nonlocal found
            found = True
            return (0,x)
        return (1,x)
    values.sort(key=helper)
    return found
numbers = [8,3,1,2,5,4,7,6]
group = [8,5,2,3,4,7,9]
found = sort_priority2(numbers,group)
print('最后的numbers',numbers)
print("found",found)
输出:最后的numbers [2, 3, 4, 5, 7, 8, 1, 6]
found True

class Sorter(object):
    def __init__(self,group):
        self.group = group
        self.found = False
    def __call__(self,x):
        if x in self.group:
            self.found = True
            return (0,x)
        return (1,x)
group = [8,5,2,3,4,7,9]
numbers = [8,3,1,2,5,4,7,6]
sorter = Sorter(group)
numbers.sort(key=sorter)
assert sorter.found is True
print(sorter.found)

student_tuples = [
    ('john', 'A',20, 15),
    ('jane', 'B',21, 12),
    ('dave', 'B', 22,10),
 ]
print(sorted(student_tuples, key=lambda student: student[0]))   # sort by age
# [('dave', 'B', 10), ('jane', 'B', 12), ('john', 'A', 15)]

L = [{1:5,3:4},{1:3,6:3},{1:1,2:4,5:6},{1:9}]
def f(x):
    return len(x)
L.sort(key=f) #reverse = True #怎样在此处天加速reverse
print (L)