ArrayFormula, RegexExtract, and Join in Google Sheets - google-sheets

Question

I have a data set wherein emails are populated. I would like to list all the surnames extracted in the emails per cell and will be all joined to a one single cell but I want to put a separator or delimeter to the emails obtaine per cell.
Here is the data set:
A
B
john.smith#gmail.com, jane.doe#gmail.com
UPDATE
john.smith#gmail.com
CLOSE
And here is the formula to extract
=ARRAYFORMULA(
PROPER(
REGEXEXTRACT(
A:A,
REGEXREPLACE(
A:A,
"(\w+)#","($1)#"
)
)
)
)
This initially yields the ff:
C
D
Smith
Doe
Smith
I would like to use JOIN() inside the ARRAYFORMULA() but it is not working as I seem to think it would since it outputs an error that it only accepts one row or one column of data. My initial understanding of ARRAYFORMULA() is that it iterates through the course of the data, so I thought it will JOIN() first, and then move on to the next element/row but I guess it doesn't work that way. I can use FLATTEN() but I want to have delimiters or separators in between the row elements. I need help in obtaining my intended final result which will look like this:
UPDATE:
Smith
Doe
CLOSE:
Smith
All are located in one cell, C1. UPDATE and CLOSE are from column B.
EDIT: I would like to clarify that the email entries in column A are dynamic and maybe more than two.

Answer 1

I think this will work:
=arrayformula(flatten(if(A2:A<>"",regexreplace(trim(split(B2:B&":"&char(9999)&regexreplace(Proper(A2:A),"#[\w\.]+,\ ?|#.*",char(9999)&" "),char(9999))),".*\.",),)))
NOTES:
Proper(A2:A) changes the capitalisation.
The regexreplace "#[\w\.]+,\ ?|#.*" finds:
# symbol...
then any number of A-Z, a-z, 0-9, _ [using \w] or . [using \.]
then a comma
then 'optionally' a space \ [the optional bit is ?]
or [using |], the # symbol then an number of characters [using .*]
The result is replaced with a character that you won't expect to have in your text - char(9999) which is a pencil icon, and a trailing space (used later on when the flatten keeps a gap between lines). The purpose is to get all of the 'name.surname' and 'nameonly' values in front of any # symbol and separate them with char(9999).
Then infront of the regexreplace is B2:B&":"&char(9999)& which gets the value from column B, the : chanracter and char(9999).
The split() function then separates then into columns. Trim() is used to get rid of spaces in front of names that don't contain ..
The next regexreplace() function deletes anything before, and including . to keep surname or name without ..
The if(A2:A<>"" only process rows where there is a value in col A. The arrayformula() function is required to cascade the formula down the sheet.
I didn't output the results in a single cell, but it looks like you've sorted that with textjoin.
Here's my version of getting the results into a single cell.
=arrayformula(textjoin(char(10),1,if(A2:A<>"",REGEXREPLACE(B2:B&":"&char(10)&regexreplace(Proper(A2:A),"#[\w\.]+,\ ?|#.*",char(10)),".*\.",),)))

Answer 2

Assuming that your A:A cells will always contain only contiguous email addresses separated by commas, you could place this in, say, C1 (being sure that both Columns C and D are otherwise empty beforehand):
=TRANSPOSE(FILTER({B:B,IFERROR(REGEXEXTRACT(SPLIT(PROPER(A:A),","),"([^\.]+)#"))},A:A<>""))
If this produces the desired result and you'd like to know how it works, report back. The first step, however, is to make sure it works as expected.

Answer 3

use:
=INDEX(REGEXREPLACE(TRIM(QUERY(FLATTEN(QUERY(TRANSPOSE({{B1; IF(B2:B="",,"×"&B2:B)},
PROPER(REGEXEXTRACT(A:A, REGEXREPLACE(A:A, "(\w+)#", "($1)#")))})
,,9^9)),,9^9)), " |×", CHAR(10)))