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:
map
reduce
str2float
'123.456'
123.456
# -*- coding: utf-8 -*- from functools import reduce 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 fn1(x, y): return x * 10 + y def fn2(i,j): return 0.1*i+j def char2num(s): return DIGITS[s] m= s.split('.')[0] n= s.split('.')[1] m1=list(map(char2num,m)) n1=list(map(char2num,n))[::-1] print(n1) return reduce(fn1, m1)+reduce(fn2,n1)*0.1
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!')