问题描述
如果我只是在这里阅读我的 sum_digits 函数,这在我的脑海中是有道理的,但它似乎产生了错误的结果.有什么建议吗?
if i just read my sum_digits function here, it makes sense in my head but it seems to be producing wrong results. Any tip?
def is_a_digit(s): ''' (str) -> bool Precondition: len(s) == 1 Return True iff s is a string containing a single digit character (between '0' and '9' inclusive). >>> is_a_digit('7') True >>> is_a_digit('b') False ''' return '0' <= s and s <= '9' def sum_digits(digit): b = 0 for a in digit: if is_a_digit(a) == True: b = int(a) b += 1 return b
对于函数sum_digits,如果我输入sum_digits('hihello153john'),它应该产生9
For the function sum_digits, if i input sum_digits('hihello153john'), it should produce 9
推荐答案
请注意,您可以使用内置函数轻松解决此问题.这是一个更惯用和更有效的解决方案:
Notice that you can easily solve this problem using built-in functions. This is a more idiomatic and efficient solution:
def sum_digits(digit): return sum(int(x) for x in digit if x.isdigit()) print(sum_digits('hihello153john')) => 9
特别要注意,对于字符串类型已经存在 is_a_digit() 方法,它被称为 isdigit().
In particular, be aware that the is_a_digit() method already exists for string types, it's called isdigit().
sum_digits() 函数中的整个循环可以使用生成器表达式作为 sum() 内置函数的参数更简洁地表示,如如上所示.
And the whole loop in the sum_digits() function can be expressed more concisely using a generator expression as a parameter for the sum() built-in function, as shown above.