How to exclude string of patten in regex search

Question

How to use regex to search word in the html string, but ignore the word in html tags. For example <a href="foo">foo</a>, the first foo in should be ignored, the second foo is the pattern to search.

Are you looking for a bullet-proof solution? Or one that works with just that specific string? — 4castle, Aug 12 '16 at 05:16
Instead of regex, you should use an HTML parser. Try `beautifulsoup` — juanpa.arrivillaga, Aug 12 '16 at 05:19
An approach that works in many cases is `<[^>]+>|(foo)`. From there you can find the matches that have a first capture group. It breaks though when the attributes contain `>`. — 4castle, Aug 12 '16 at 05:35
[`re.sub(r'<[^<]+?>|(foo)', lambda m: "{}".format(m.group(1)) if m.group(1) else m.group(), s)`](https://ideone.com/6Z2Zr0) will work in any Python version. — Wiktor Stribiżew, Aug 12 '16 at 06:59

score 1 · Answer 1 · edited May 23 '17 at 12:08

1

An example using BeautifulSoup combined with regex instead:

from bs4 import BeautifulSoup
import re

string = '''
<a class='fooo123'>foo on its own</a>
<a class='123foo'>only foo</a>
'''

soup = BeautifulSoup(string, "lxml")
foo_links = soup.find_all(text=re.compile("^foo"))
print(foo_links)
# ['foo on its own']

To wrap the found links with e.g. mark, you can do the following:

from bs4 import BeautifulSoup
import re

string = '''
<a class='fooo123'>foo on its own</a>
<a class='123foo'>only foo</a>
'''

soup = BeautifulSoup(string, "lxml")
foo_links = soup.findAll('a', text=re.compile("^foo"))
for a in foo_links:
    mark = soup.new_tag('mark')
    a.wrap(mark)

print(soup.prettify())

As well as the mandatory Tony the Pony link...

edited May 23 '17 at 12:08

Community

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answered Aug 12 '16 at 05:38

Jan

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Thanks for the example. The search works. Do you have any idea to highlight the matched item as well? Basically, replace the `foo` with `foo`. I also found that BeautifulSoup is much slower than `regex`, the search with `beautifulsoup` takes about 1.5 seconds while `regex` takes only 5ms (`re.compile("foo", string)`). Maybe because I do not have the correct search pattern? I also tried regex `re.compile("(?:<.*>.*)(foo)")`, it is even longer with 3.830 seconds. – Tmx Aug 12 '16 at 05:58
@Tmx: Updated the answer. – Jan Aug 12 '16 at 08:07

score 1 · Answer 2 · answered Aug 12 '16 at 06:54

This program should be able to find all the contents between tags.

import re

str = '''<h3>
            <a href="//stackexchange.com/users/838793061/?accounts">yourcommunities</a>
    </h3>

        <a href="#" id="edit-pinned-sites">edit</a>
        <a href="#" id="cancel-pinned-sites"style="display:none;">cancel</a>'''

pattern = re.compile(r'>([^<>]+)<')
all = re.findall(pattern, str)

for i in all:
    print(i)

score 0 · Answer 3 · answered Aug 20 '16 at 23:10

What if the content contains spaces?

I propose the next regex that also removes the spaces from the answer:

#### With spaces:
line = '<a href="foo">     foo       </a>'
re.findall(r'>\s*(\w*)\s*<',line)
### ['foo']

#### No spaces:
line = '<a href="foo">foo</a>'
re.findall(r'>\s*(\w*)\s*<',line)
### ['foo']

How to exclude string of patten in regex search

3 Answers3