Extracting multiple rows from text file based on a header row

[Ross Brown]

Hi everyone

First time posting on here so apologies in advance if this is a stupid question or has already been asked (I have looked in the community but can’t find a similar question)

I want to be able to bookmark blocks of rows based on a header row so I can copy them into a new file.

I am looking to extract the data for header rows “AAA A AA”
I then want to extract the header row itself and all the rows under it up until the next AAA row. So including the ZZZ, YYY, WWW, BBB rows (rows 1-16, 26-34)

I want to exclude all data for the header rows that do not match the above for instance in this data set those with “AAA A ZZ” (rows 17-25, 35)

Is this possible with Regex?

Thanks in advance! 👏👊

[Alan Kilborn]

@Ross-Brown

Try: (?s-i)^AAA A {3}AA.*?(?=^AAA|\z)

Notes about the {3}:

• I’m guessing that there are 3 spaces between the A by itself and the ending AA
• I first tried to write the expression with 3 real spaces instead of a single space followed by {3} but, even though I used special markdown syntax, this site still compressed multiple spaces to a single space character

[Ross Brown]

@Alan-Kilborn said in Extracting multiple rows from text file based on a header row:

(?s-i)^AAA A {3}AA.*?(?=^AAA|\z)

Alan

Correct it was a AAA [single space] A [3 spaces] AA

Amazingly quick response and this works perfectly! You have inspired me to learn Regex. Virtual high 5!

One small query (if its not too much trouble) I have a slightly different data set where I also need to extract the row before the one with the header data is that possible?

Thanks!

[Alan Kilborn]

@Ross-Brown said in Extracting multiple rows from text file based on a header row:

I have a slightly different data set where I also need to extract the row before the one with the header data is that possible?

Try: (?-i)(?-s)^.+?\R^AAA A {3}AA(?s).*?(?=^AAA|\z)

but… be aware that with that need you create a conflict: if you have two “desired” sections adjacent in the file, the second one won’t match (without further work on the expression).

@Ross-Brown said in Extracting multiple rows from text file based on a header row:

You have inspired me to learn Regex.

If true, and it happens, this warms my heart. :-)

[Ross Brown]

@Alan-Kilborn said in Extracting multiple rows from text file based on a header row:

(?-i)(?-s)^.+?\R^AAA A {3}AA(?s).*?(?=^AAA|\z)

Amazing, thanks! This is a real help

I will learn it at some point, just need to find the time to invest in myself so I can see the benefits.