Question

我正在尝试解析txt文件中两个不同标签的内容，而我正在获取第一个标签的所有实例＆＃34; p＆＃34;但不是第二个＆＃34; l＆＃34;。问题是＆＃34;或＆＃34;？

感谢您的帮助。这是我正在使用的代码

with open('standardA00456.txt','w') as output_file:
    with open('standardA00456.txt','r') as open_file:
            the_whole_file = open_file.read()
            start_position = 0

            while True:

               start_position = the_whole_file.find('<p>' or '<l>', start_position)

               end_position = the_whole_file.find('</p>' or '</l>', start_position)
               data = the_whole_file[start_position:end_position+5]


               output_file.write(data + "\n")
               start_position = end_position

Answer 1

'<p>' or '<l>'将始终等于'<p>'，因为它告诉Python仅在'<l>'为'<p>'，None时使用False，数字为零，或空。由于字符串'<p>'永远不会是其中之一，因此始终会跳过'<l>'：

>>> '<p>' or '<l>'
'<p>'
>>> None or '<l>'
'<l>'

相反，您可以轻松使用re.findall：

import re
with open('standardA00456.txt','w') as out_f,  open('standardA00456.txt','r') as open_f:
    p_or_ls = re.findall(r'(?:<p>.*?</p>)|(?:<l>.*?</l>)', 
                         open_f.read(), 
                         flags=re.DOTALL) #to include newline characters
    for p_or_l in p_or_ls:
        out_f.write(p_or_l + "\n")

但是，使用正则表达式解析带有标记（例如HTML和XML）的文件是 not a good idea 。使用BeautifulSoup之类的模块更安全：

from bs4 import BeautifulSoup
with open('standardA00456.txt','w') as out_f,  open('standardA00456.txt','r') as open_f:
    soup = BeautifulSoup(open_f.read())
    for p_or_l in soup.find_all(["p", "l"]):
        out_f.write(p_or_l + "\n")

Answer 2

英语Grad，我认为你需要改进逻辑。我修改了你的代码并想出了这个：

with open('standardA00456.txt','w') as output_file:
    with open('standardA00456.txt','r') as open_file:
        the_whole_file = open_file.read()
        start_position = 0

        found_p = False
        fould_l = False

        while True:
            start_pos_p = the_whole_file.find('<p>', start_position)
            start_pos_l = the_whole_file.find('<l>', start_position)

            if start_pos_p > -1 and start_pos_l > -1:
                if start_pos_p < start_pos_l:
                    found_p = True
                    start_position = start_pos_p
                    found_l = False
                else:
                    found_l = True
                    start_position = start_pos_l
                    found_p = False
            elif start_pos_p > -1:        
                found_p = True
                start_position = start_pos_p
                found_l = False
            elif start_pos_l > -1:        
                found_l = True
                start_position = start_pos_l
                found_p = False
            else:
                break

            if found_p:
                end_position = the_whole_file.find('</p>', start_position)

            elif found_l:
                end_position = the_whole_file.find('</l>', start_position)

            else:
                break

            data = the_whole_file[start_position:end_position+5]
            output_file.write(data + "\n")
            start_position = end_position

Python txt文件标记解析

2 个答案: