def str2float(s):    DIGITS = {'0': 0, '1': 1, '2': 2, '3': 3, '4': 4, '5': 5, '6': 6, '7': 7, '8': 8, '9': 9}    def cheng(x, y):        #整数部分        return x * 10 + y    def chu(x, y):          #小数部分        if x>=1:            return x/100+y/10        else:            return x/10+y/10    def str2num(k):         #字符串转整数        return DIGITS[k]    max = len(s)    zhengshu=[]    xiaoshu=[]    i = 0    while i < max:          #字符串以. 分割,也可以直接用.split()        if s[i] != '.':            zhengshu.append(s[i])            i=i+1        else:            xiaoshu=s[-1:i:-1]    #逆向存储            break    res = reduce(cheng, map(str2num, zhengshu)) + reduce(chu, map(str2num, xiaoshu))    return res