重复字符串一定长度

def repeat_to_length(string_to_expand, length):   return (string_to_expand * ((length/len(string_to_expand))+1))[:length]

对于python3：

def repeat_to_length(string_to_expand, length):    return (string_to_expand * (int(length/len(string_to_expand))+1))[:length]