CODEWITHSUNDEEP
pythonparsingtext
English Grad
English Grad

Reputation: 1395

Python txt file tag parse

I am trying to parse out the contents of two different tags in a txt file and I am getting all the instances of the first tag "p" but not the second "l". Is the problem with the "or"?

Thanks for the help. Here is the code I am using

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

Upvotes: 1

Views: 1660

Answers (2)

dwitvliet
dwitvliet

Reputation: 7671

'<p>' or '<l>' will always equal '<p>', as it tells Python to use '<l>' only if '<p>' is None, False, numeric zero, or empty. And as the string '<p>' is never one of those, '<l>' is always skipped:

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

Instead you can easily use 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")

However, parsing files with tags (such as HTML and XML) using regex is not a good idea. Using a module, such as BeautifulSoup is safer:

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")

Upvotes: 1

Tamim Shahriar
Tamim Shahriar

Reputation: 739

English Grad, I think you need to improve the logic. I modified your code and came up with this: 

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

Upvotes: 0

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