如何用信息代替星星的图案？

Question

我正试图通过按照以下模式重复邮件中的项目来格式化邮件：

message = '123'
pattern = '** *** **** * **'

预期输出：12 312 3123 1 23

下面是我当前的代码，但是输出：123 12 31 231 23

def main():

    message = "123"
    
    pattern = "** *** ** ** *"
    print(patterned_message(message, pattern))

def patterned_message(message, pattern):
    
    c = 0
    res = ""
    jstr = [x.strip(" ") for x in message]
    for i in pattern:
        if c == (len(jstr)):
            c = 0
        else:
            if i == " ":
                res += " "
            else:
                res += i.replace("*","{}".format(jstr[c]))
                c += 1
          
    return res        

   

if __name__ == '__main__':
    main()

Answer 1

您可以使用itertools.cycle作为生成器和小列表：

from itertools import cycle

message = '123'
pattern = '** *** **** * **'

x = cycle(message)

out = ''.join(next(x) if i == '*' else ' ' for i in pattern)

print(out)

输出：'12 312 3123 1 23'

对于python学习者，这里有一种更经典的方法：

def patterned_message(message, pattern):
    out = [' ']*len(pattern)
    n = 0
    for i, char in enumerate(pattern):
        if char == '*':
            out[i] = message[n%len(message)]
            n+=1
    return ''.join(out)

patterned_message('123', '** *** **** * **')