Regular expression: Match everything after a particular word until multiple occurence of carriage return and new line

Question

I am using Python and would like to match all the words after "Examination(s):" till one or more empty lines occur.

text = "Examination(s):\sMathematics 2nd Paper\r\n\r\nTimeTable"
text = "Examination(s):\r\n\r\nMathematics 2nd Paper\r\nblahblah"
text = "Examination(s):\r\nMathematics 2nd Paper\r\n\r\n\r\nmarks"

In all the above examples, my output should be "Mathematics 2nd Paper". Here is what I tried:

import re
pat = re.compile(r'(?:Examination\(s\):)[^\r\n]*')
re.search(pat,text)

The above snippet works fine for example 2 (one occurrence of \r\n), but is not working for examples 1 and 3.

I am getting this error when i tried to apply your pattern @Wiktor

Updating the question to capture the missed scenario, it can be a space or newline after colon

[![enter image description here][2]][2]

@AmirhosseinKiani Your regex test is invalid, you are not testing against the literal text, but against a string literal. — Wiktor Stribiżew, Feb 19 '22 at 11:12
@WiktorStribiżew Can you be more specific? By "literal text" do you mean a text file? — TheFaultInOurStars, Feb 19 '22 at 11:14
@AmirhosseinKiani All you need to know is available at [Regular expression works on regex101.com, but not on prod](https://stackoverflow.com/a/39636208/3832970), scroll to *All languages - "Literal string" vs. "String literal" alert* section. — Wiktor Stribiżew, Feb 19 '22 at 11:16
Ok, so what about `re.search(r'Examination\(s\):\r?\n([^\r\n]+)', text)`? See [this Python demo](https://ideone.com/bpYwTE). — Wiktor Stribiżew, Feb 19 '22 at 11:19
I wonder if there is a reason for using `[^\r\n]+` instead of `.+` — bobble bubble, Feb 19 '22 at 15:05

Wiktor Stribiżew · Accepted Answer · 2022-02-19T11:38:56.950

1

To get the line after Examination(s): you can use

re.search(r'Examination\(s\):\s*([^\r\n]+)', text)

See the regex demo. Details:

Examination\(s\): - a literal Examination(s): string
\s* - zero or more whitespaces
([^\r\n]+) - Group 1: one or more chars other than CR and LF chars.

See the Python demo:

import re
texts = ["Examination(s):\r\nMathematics 2nd Paper\r\n\r\nTimeTable",
    "Examination(s):\r\nMathematics 2nd Paper\r\nblahblah",
    "Examination(s):\r\nMathematics 2nd Paper\r\n\r\n\r\nmarks"]
 
for text in texts:
    m = re.search(r'Examination\(s\):\s*([^\r\n]+)', text)
    print(f'--- {repr(text)} ---')
    if m:
        print(m.group(1))

Output:

--- 'Examination(s):\r\nMathematics 2nd Paper\r\n\r\nTimeTable' ---
Mathematics 2nd Paper
--- 'Examination(s):\r\nMathematics 2nd Paper\r\nblahblah' ---
Mathematics 2nd Paper
--- 'Examination(s):\r\nMathematics 2nd Paper\r\n\r\n\r\nmarks' ---
Mathematics 2nd Paper

edited Feb 19 '22 at 11:38

answered Feb 19 '22 at 11:24

Wiktor Stribiżew

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I am getting an error, uploaded the screenshot of the error in my question. Thank you. – dsj Feb 19 '22 at 11:35
1

@dsj Because there is no match, in that string, you do not have a line break after `:` and all the strings in the question contain a line break there. Replace `\r?\n`, or `[\r\n]+`, with `(?:\r?\n)?` or a more generic `\s*` then. – Wiktor Stribiżew Feb 19 '22 at 11:38
Apologies yes you are right, it worked now, but yes it will have space in some text, newline in some text, does \s* works for all that cases? – dsj Feb 19 '22 at 11:41
1

@dsj `\s*` matches zero or more whitespaces, all Unicode whitespaces. – Wiktor Stribiżew Feb 19 '22 at 11:43
Ah yes, it fails whenever there is newline character in there, how do I match both spaces and newlines here? Because some examples will have space, some will have one newline, some will have 2 new lines. – dsj Feb 19 '22 at 11:45
@dsj See a [Whitespace](https://en.wikipedia.org/wiki/Whitespace_character) wiki article. – Wiktor Stribiżew Feb 19 '22 at 11:47
It works, thank you. updated the examples in the question to captured missed ones. Apologies, Thanks for pointing out. – dsj Feb 19 '22 at 11:51

Regular expression: Match everything after a particular word until multiple occurence of carriage return and new line

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