python中的map函数

Posted 2021-01-05 jiyanjiao

 1 def f(x):
 2     return x * x
 3 
 4 
 5 """将一个全是数字的list变成平方形式"""
 6 
 7 
 8 def f2():
 9     ls = [1, 2, 3, 4, 5]
10     r2 = map(f, ls)
11     print(list(r2))
12 
13 
14 """将list的值均变为字符串"""
15 
16 
17 def str2():
18     ls = [‘a‘, 2, 3, 4, 5]
19     ls2 = map(str, ls)
20     print(ls2)
21     print(list(ls2))
22 
23 
24 """将一个list里的首字母大写,后续字母小写"""
25 
26 
27 def format_name(s):
28     s1 = s[0:1].upper() + s[1:].lower()
29     return s1
30 
31 
32 def slower():
33     L = [‘jiyanjiao‘, ‘jiyanjiao‘, ‘jiyanjiao‘, ‘jiyanjiao‘]
34     m = 0
35     for i in L:
36         L[m] = i[0:1].upper() + i[1:]
37         m = m + 1
38     for index, name in enumerate(L):
39         print(index, ‘-‘, name)
40         # enumerate() 函数用于将一个可遍历的数据对象(如列表、元组或字符串)组合为一个索引序列，同时列出数据和数据下标，一般用在 for
41         # 循环当中。
42 
43 f2()
44 str2()
45 slower()
46 
47 """打印结果
48 [1, 4, 9, 16, 25]
49 <map object at 0x0000018601F31390>
50 [‘a‘, ‘2‘, ‘3‘, ‘4‘, ‘5‘]
51 0 - Jiyanjiao
52 1 - Jiyanjiao
53 2 - Jiyanjiao
54 3 - Jiyanjiao
55 
56 
57 """