Extract strings in python

Question

Basically, I want to extract the strings "AAA", "BBB", "CCC", "DDD" from a text file...

...... (other text goes here).....
<TD align="left" class=texttd><font class='textfont'>AAA</font></TD>
..... (useless text here).....
<TD align="left" class=texttd><font class='textfont'>BBB</font></TD>
....(more text).....
<TD align="left" class=texttd><font class='textfont'>CCC</font></TD>
<TD align="left" class=texttd><font class='textfont'>DDD</font></TD>
......(more text).....

I want something like if I do:-

data = foo("file.txt")

I get:-

data = ['AAA','BBB','CCC','DDD']

What is the best possible way? My file is not big...

Basically, I want to extract "remaining upload data transfer" from this file which in HTML looks like THIS

Answer 1

You could write a REGEX but it would be "parsing" the HTML to some extent. The problem with writing regular expressions for HTML is HTML is a mess. It's rarely perfect and this causes problems when you rely on it for data.

I would personally use BeautifulSoup. It does do more than you're asking but also at superfraction of the effort.

Answer 2

You want BeautifulSoup:

from BeautifulSoup import BeautifulSoup
soup = BeautifulSoup(your_file)

soup.find("font", "textfont")

Answer 3

def foo():
    input_file = open("myfile.txt", 'r')
    input = ''.join(input_file.readlines())

    looking_for = ['AAA', 'BBB', 'CCC', 'DDD']
    have = []

    for thing in looking_for:
        if thing in input:
            have.append(thing)
    return have

Answer 4

In a case like this it's, attempt regex for it ( which will be really had ), use a prewritten library, or do it your self with a f = open() f.read() and your own parser.

Answer 5

If you just want to get the data from inside all of the tags in the HTML document, while dropping all the tags themselves, you could do something like this:

import HTMLParser

class DataOnlyParser(HTMLParser.HTMLParser):
    def parse(self, text):
        self.result = []
        self.feed(text)
        self.close()
        return self.result

    def handle_data(self, data):
        data = data.strip()
        if data:
            self.result.append(data)

p = DataOnlyParser()

data = """
<TD align="left" class=texttd><font class='textfont'>AAA</font></TD>
<TD align="left" class=texttd><font class='textfont'>BBB</font></TD>
<TD align="left" class=texttd><font class='textfont'>CCC</font></TD>
<TD align="left" class=texttd><font class='textfont'>DDD</font></TD>
"""

print p.parse(data)
# ['AAA', 'BBB', 'CCC', 'DDD']

If your selection criteria is more complex though, and/or if the input is malformed, you'd probably be better off with a library like lxml.

You do NOT want to use regular expressions to "parse" html. See here.