列表sort()方法

>>> help(list.sort)
Help on method_descriptor:

sort(...)
    L.sort(key=None, reverse=False) -> None -- stable sort *IN PLACE*

a=[2,3,2,5,6,8,9,0,1,6,7,12]
a.sort()
print(a)
>>>[0, 1, 2, 2, 3, 5, 6, 6, 7, 8, 9, 12]

a=[‘aaa‘,‘aaaa‘,‘a‘,‘aa‘]
a.sort(key=len)
print(a)
>>>[‘a‘, ‘aa‘, ‘aaa‘, ‘aaaa‘]

 #要求1.正数在前负数在后 2.正数从小到大 3.负数从大到小
a=[7,3, -8, 5, 4, 0, -2, -5]
a.sort(key=lambda x:(x<0,abs(x)))
print(a)
>>>[0, 3, 4, 5, 7, -2, -5, -8]

a=[7,3, -8, 5, 4, 0, -2, -5]
b=a[:]
a.sort()
b.sort(reverse=True)
print(a)
print(b)
>>>
[-8, -5, -2, 0, 3, 4, 5, 7]
[7, 5, 4, 3, 0, -2, -5, -8]