【Python实践-9】将字符串转化为浮

 1 from functools import reduce
 2 def str2float(s):
 3     DIGITS = {'0': 0, '1': 1, '2': 2, '3': 3, '4': 4, '5': 5, '6': 6, '7': 7, '8': 8, '9': 9}
 4     b=0#计算小数位数
 5     i=0
 6     while i<len(s):
 7         if s[i]=='.':
 8             b=len(s)-i-1
 9         i=i+1
10 
11     s=s[:(len(s)-b-1)]+s[(len(s)-b):]
12     #字符转换为整数
13     def f1(s):
14         return DIGITS[s]
15     #exp:1,2转换为12
16     def f2(a,b):
17         return a*10+b
18     def f3(s):#整数转换为浮点数
19         for i in range(b):
20             s=s*0.1
21         return s
22     return (f3(reduce(f2,map(f1,s))))
23 print(str2float('12.3456'))

reduce(f, [x1, x2, x3, x4]) = f(f(f(x1, x2), x3), x4)