Extracting text from string using Regex

Question

I have a very large string. There are many paragraphs inside that string. Each paragraph starts with a title and follows a particular pattern.

Example:

== Title1 == // Paragraph starts ............. ............. // Some texts ............. End of Paragraph ===Title2 === // Paragraph starts ............. ............. // Some texts .............

The pattern of the title are:

1.) New Paragraph title starts with an equal to ( = ) and can be followed by any number of =.

2.) After = , there can be a white space ( not necessary though ) and it is followed by text.

3.) After text completion, again there can be a white space ( not necessary ), followed by again any number of equal to's ( = ).

4.) Now the paragraph starts. I have to extract the text until it encounters a similar pattern.

Can anyone help me with how to do this with regex? TIA

Answer 1

You may use

re.findall(r'(?m)^=+[^\S\r\n]*(.*?)[^\S\r\n]*=+\s*(.*(?:\r?\n(?!=+.*?=).*)*)', s)

See the regex demo

Details

• (?m)^ - start of a line
• =+ - 1 or more = chars
• [^\S\r\n]* - zero or more whitespace chars other than CR and LF
• (.*?) - Group 1: any zero or more chars, other than line break chars, as few as possible
• [^\S\r\n]* - zero or more whitespace chars other than CR and LF
• =+ - 1 or more = chars
• \s* - 0+ whitespaces
• (.*(?:\r?\n(?!==+.*?=).*)*) - Group 2:
  • .* - any zero or more chars, other than line break chars, as many as possible
  • (?:\r?\n(?!=+.*?=).*)* - zero or more sequences of
    • \r?\n(?!=+.*?=) - an optional CR and then LF that is not followed with 1+ =s, then any chars other than line break chars as few as possible and then again 1+ =s
    • .* - any zero or more chars, other than line break chars, as many as possible

Python demo:

import re

rx = r"(?m)^=+[^\S\r\n]*(.*?)[^\S\r\n]*=+\s*(.*(?:\r?\n(?!=+.*?=).*)*)"
s = "== Title1 ==\n..........................\n.............\nEnd of Paragraph\n===Title2 ===\n.............\n.............\n............."
print(re.findall(rx, s))

Output:

[('Title1', '..........................\n.............\nEnd of Paragraph'), ('Title2', '.............\n.............\n.............')]

Answer 2

May be this helps for finding each paragraphs Title and lines of each paragraph.

text = """== Title1 == // Paragraph starts
.............
............. // Some texts
.............
End of Paragraph
===Title2 === // Paragraph starts
.............
............. // Some texts
.............
"""
import re

reg = re.compile(r'(?:[=]+\s*\w+\s*[=]+)')

for i in text.split('\n'):
    if re.search(reg, i):
        t = re.sub(r'=', '', i)
        print('Title:', t.strip())
    else:
        print('line:', i.strip())

 # Output like this
   Title: Title1  // Paragraph starts
   line: .............
   line: ............. // Some texts
   line: .............
   line: End of Paragraph
   Title: Title2  // Paragraph starts
   line: .............
   line: ............. // Some texts
   line: .............
   line: