通过生成器迭代时发生IndexError

Question

我想为我的编程类解决问题。我收到一个包含电子邮件和特殊文件的文件夹。特殊文件始终以“！”开头。我应该在Corpus类中添加一个方法emails（）。该方法应该是一个生成器。这是其使用的例子：

corpus = Corpus('/path/to/directory/with/emails') 
count = 0 
# Go through all emails and print the filename and the message body 
for fname, body in corpus.emails(): 
    print(fname) 
    print(body) 
    print('-------------------------') 
    count += 1 
print('Finished: ', count, 'files processed.') 

这是类和我写的方法：

class Corpus: 
    def __init__(self, path_to_mails_directory): 
     self.path_to_mails_directory = path_to_mails_directory 

    def emails(self): 
    iterator = 0 
    mail_body = None 
    mails_folder = os.listdir(self.path_to_mails_directory) 
    lenght = len(mails_folder) 
    while iterator <= lenght: 
     if not mails_folder[iterator].startswith("!"): 
      with open(self.path_to_mails_directory+"/"+mails_folder[iterator]) as an_e_mail: 
       mail_body = an_e_mail.read() 
      yield mails_folder[iterator], mail_body 
     iterator += 1 

，我试图运行示例代码是这样的：

if __name__ == "__main__": 
    my_corpus = Corpus("data/1") 
    my_gen = my_corpus.emails() 
    count = 0 
    for fname, body in my_gen: 
     print(fname) 
     print(body) 
     print("------------------------------") 
     count += 1 
    print("finished: " + str(count)) 

Python按预期打印了一堆邮件（该文件夹包含大约一千个文件），然后执行：

Traceback (most recent call last): 
    File "C:/Users/tvavr/PycharmProjects/spamfilter/corpus.py", line 26, in <module> 
    for fname, body in my_gen: 
    File "C:/Users/tvavr/PycharmProjects/spamfilter/corpus.py", line 15, in emails 
    if not mails_folder[iterator].startswith("!"): 
IndexError: list index out of range 

我不知道问题是什么，并希望得到任何帮助。 Thx

编辑：我更新了一些基于您的建议的代码。

Answer 1

一个好办法做到这将是如下：基于

def emails(self): 
    mail_body = None 
    mails_folder = os.listdir(self.path_to_mails_directory) 
    for mail in mails_folder: 
     if mail.startswith("!"): 
      pass 
     else: 
      with open(self.path_to_mails_directory+"/"+mail) as an_e_mail: 
       mail_body = an_e_mail.read() 
      yield mail, mail_body 

指数迭代不被认为是Python的。你应该更喜欢“邮件在mails_folder：”语法。