常用内置函数-6

zip:   匹配

>>> k = ['name','year','where']
>>> massage = ['tang','18','nc']

>>> other = [1,2,3]
>>> list(zip(k,massage))
[('name', 'tang'), ('year', '18'), ('where', 'nc')]

>>> list(zip(k,massage,other))
[('name', 'tang', 1), ('year', '18', 2), ('where', 'nc', 3)]

lambda:

>>> a =lambda x: x +1
>>> a(2)
3

filter过滤：

>>> li = [1,2,3]
>>> a =lambda x: x >2
>>> b = filter(a,li)
>>> list(b)
[3]

map: 加工

>>> a =lambda x: x +1
>>> li = [1,2,3]
>>> c=map(a,li)
>>> c
<map object at 0x0000014A0F4A86D8>
>>> list(c)
[2, 3, 4]

>>> li = [1,2,3]
>>> a =lambda x: x >1
>>> c=map(a,li)
>>> list(c)
[False, True, True]

enumerate枚举：

>>> li=['a','b','c','d']
>>> list(enumerate(li))
[(0, 'a'), (1, 'b'), (2, 'c'), (3, 'd')]
>>> list(enumerate(li,10))
[(10, 'a'), (11, 'b'), (12, 'c'), (13, 'd')]

for k,v in enumerate(li):
print(k,v)

>>>

0 a
1 b
2 c
3 d

进制，ascaii:

bin(3) # '0b11' 二进制前缀 0b
oct(9) # '0o11'
hex(17) # '0x11'

ord('a')
ord('A')
chr(65)
chr(97)

sorted:

sorted(iterable, /, *, key=None, reverse=False)

1)对于一个列表排序

sorted([100, 98, 102, 1, 40])
>>>[1, 40, 98, 100, 102]

2)通过key参数/函数

比如一个长列表里面嵌套了很多字典元素，我们要按照每个元素的长度大小排序

L = [{1:5,3:4},{1:3,6:3},{1:1,2:4,5:6},{1:9}]
new_line=sorted(L,key=lambda x:len(x))
print(new_line)
>>>[{1: 9}, {1: 5, 3: 4}, {1: 3, 6: 3}, {1: 1, 2: 4, 5: 6}]

3)对由tuple组成的List排序

比如下面是学生里面的年龄的一个list

students = [('wang', 'A', 15), ('li', 'B', 12), ('zhang', 'B', 10)] 
print(sorted(students, key=lambda x : x[2]))
>>>[('zhang', 'B', 10), ('li', 'B', 12), ('wang', 'A', 15)]