【python练习】利用map和reduce编写一个str2float函数，把字符串‘123.456‘转换成浮点数123.456

from functools import reduce
def str2float(s):
    def fn(x,y):
        return x*10+y
    n=s.index('.')
    s1 = list(map(int, [x for x in s[:n]]) )
    s2 = list(map(int, [x for x in s[n+1:]]))
    return reduce(fn,s1)+reduce(fn,s2)/10**len(s2)
print('str2float(\'123.456\') =', str2float('123.456'))
if abs(str2float('123.456') - 123.456) < 0.00001:
    print('测试成功!')
else:
    print('测试失败!')