Question

我在Python 2.7x中运行以下代码：

def captureAlbumLinks():
    for page in index_pages: # index_pages is a list of URLs
        resp = connect_tor(page)
        soup = BeautifulSoup(resp.read(), from_encoding=resp.info().getparam('charset'))
        try:
            # The below two variables relate to URLs of type string
            x = pickle.load(open("last_passworded_album.p", "rb"))
            y = pickle.load(open("last_accessible_album.p", "rb"))
        except:
            print "There is no pickle file"
        for a in soup.find_all('a', href=True):
            if (root_url + a['href']) == x or (root_url) + a['href'] == y:
                break
            elif "passchk.php" in a['href']:
                passworded_albums.append(root_url + a['href'])
            elif "search.php" in a['href'] or "switch.php" in a['href']:
                pass
            else:
                if ".html" in a['href']:
                    accessible_albums.append(root_url + a['href'])

本质上，“if（root_url + a ['href']）== x或（root_url）+ a ['href'] == y：”，我不希望任何elifs运行想摆脱' for '循环。尽管如此，即使if语句运行为true（使用print语句验证），我的代码似乎也会运行到下一个'elif'。我想目前我只是打破'if'循环而不是'for'循环。

我觉得这是一个缩进问题，但尝试过移动'休息'但没有快乐。

有人可以帮忙吗？

Answer 1

有时候实用的方法是将它包装在一个函数中并返回。在你的情况下，你可以＆＃34;返回＆＃34;但一般来说，你会写一个内部函数（在这种情况下＆＃39;循环＆＃39;）

def captureAlbumLinks():
  def loops():
    for page in index_pages: # index_pages is a list of URLs
        resp = connect_tor(page)
        soup = BeautifulSoup(resp.read(), from_encoding=resp.info().getparam('charset'))
        try:
            # The below two variables relate to URLs of type string
            x = pickle.load(open("last_passworded_album.p", "rb"))
            y = pickle.load(open("last_accessible_album.p", "rb"))
        except:
            print "There is no pickle file"
        for a in soup.find_all('a', href=True):
            if (root_url + a['href']) == x or (root_url) + a['href'] == y:
                return
            elif "passchk.php" in a['href']:
                passworded_albums.append(root_url + a['href'])
            elif "search.php" in a['href'] or "switch.php" in a['href']:
                pass
            else:
                if ".html" in a['href']:
                    accessible_albums.append(root_url + a['href'])
  return loops()

Answer 2

您只需返回结束功能：

import pickle
def capture_album_links():
    for page in index_pages: # index_pages is a list of URLs
        resp = connect_tor(page)
        soup = BeautifulSoup(resp.read(), from_encoding=resp.info().getparam('charset'))
        try:
            # with will automatically close your files
            with open("last_passworded_album.p", "rb") as f1, open("last_accessible_album.p", "rb") as f2:
                x = pickle.load(f1)
                y = pickle.load(f2)
        # catch specific errors
        except (pickle.UnpicklingError,IOError) as e:
            print(e)
            print "There is no pickle file"
            # continue on error or x and y won't be defined 
            continue 
        for a in soup.find_all('a', href=True):
            if root_url + a['href'] in {x, y}:
                return # just return to end both loops
            elif "passchk.php" in a['href']:
                passworded_albums.append(root_url + a['href'])
            elif "search.php" in a['href'] or "switch.php" in a['href']:
                continue 
            else:
                if ".html" in a['href']:
                    accessible_albums.append(root_url + a['href'])

Answer 3

我喜欢将重构转换为函数并返回。您也可以将代码放在try / except块中，并在想要断开所有循环时引发异常。

Answer 4

编辑：抑制无用的评论。添加备选方案：

除了使用return之外，如果你想在循环之后做某事，你可以使用异常：

class MyException(Exception):
    pass

def captureAlbumLinks():
    try:
        for page in index_pages: # index_pages is a list of URLs
            resp = connect_tor(page)
            soup = BeautifulSoup(resp.read(), from_encoding=resp.info().getparam('charset'))
            try:
                # The below two variables relate to URLs of type string
                x = pickle.load(open("last_passworded_album.p", "rb"))
                y = pickle.load(open("last_accessible_album.p", "rb"))
            except:
                print "There is no pickle file"
            for a in soup.find_all('a', href=True):
                if (root_url + a['href']) == x or (root_url + a['href']) == y:
                    raise MyException()
                elif "passchk.php" in a['href']:
                    passworded_albums.append(root_url + a['href'])
                elif "search.php" in a['href'] or "switch.php" in a['href']:
                    pass
                else:
                    if ".html" in a['href']:
                        accessible_albums.append(root_url + a['href'])
    except MyException as e:
        pass

另一种可能不太直观的方法是在else循环中使用for子句，仅当for正常停止时才会执行（而不是break def captureAlbumLinks(): for page in index_pages: # index_pages is a list of URLs resp = connect_tor(page) soup = BeautifulSoup(resp.read(), from_encoding=resp.info().getparam('charset')) try: # The below two variables relate to URLs of type string x = pickle.load(open("last_passworded_album.p", "rb")) y = pickle.load(open("last_accessible_album.p", "rb")) except: print "There is no pickle file" for a in soup.find_all('a', href=True): if (root_url + a['href']) == x or (root_url + a['href']) == y: break elif "passchk.php" in a['href']: passworded_albums.append(root_url + a['href']) elif "search.php" in a['href'] or "switch.php" in a['href']: pass else: if ".html" in a['href']: accessible_albums.append(root_url + a['href']) else: continue break 1}}出来的）：

{{1}}

逃离Python中的嵌套循环

4 个答案: