Paragraph, HTML

It is not possible to completely parse HTML with Python regular expressions, but some parts can be extracted. With re.match and group() we can find text within tags.

When using re.match, we must specify a pattern that matches the entire HTML string. Then we can specify the tags that must surround the result.

Example

To begin, we specify a string that contains HTML tags within the Python program. In a real program, this could be loaded from an external file.

Step 1 This is the HTML data we are trying to parse. We specify this as a raw string with "r" to simplify escaping some values.

Step 2 In get_first_paragraph() we invoke re.match. The pattern matches the start and the end of the string with metacharacters.

Step 3 We check the returned match value, and then access the first group (which is text from the first parenthesis grouping).

import re

def get_first_paragraph(html):
    # Step 2: call re.match.
    # Capture the characters within the p tags.
    # Match the start and end of the html string.
    m = re.match(r"^.*<p>\s*(.+?)\s*</p>.*$", html)

    # Step 3: return first group item if groups exists.
    if m:
        return m.group(1)
    return ""

# Step 1: specify html string and call get_first_paragraph method.
html = r"<html><title>...</title><body><p>Result.</p></body></html>"
print(get_first_paragraph(html))
Result.

Some notes

Trying to access text from within HTML using Python regular expressions may not be ideal, but it usually works. There can be problems with comments, or mixed-case HTML tags.

So Be careful not to apply this style of code to all HTML documents, just a known set of them where it matches correctly.

Summary

HTML is everyone in the modern world, and Python is often used to extract text from external documents. With this logic, we can fetch at least some paragraph text.