How to get an array of column values based on multiple INDEX and MATCH matches

Question

How do you concatenate all values that match two criteria.

This is my data:

And I would like to create a summary table that I was hoping it would look like this:

My current formula (I have tried for hours), looks like this =TEXTJOIN(",",TRUE,IF(K1:O1=R2,VLOOKUP(Q3,J2:O5,MATCH(R2,K1:O1,0),FALSE),""))

but its doing something else entirely. I think I may have overcomplicated it:/. Thank you!

Answer 1

In R3 :

=LET(α,Q3:Q6,β,R2:T2,MAKEARRAY(ROWS(α),COLUMNS(β),LAMBDA(ξ,ζ,TEXTJOIN(",",1,IF(K1:O1&"|"&J2:J5=INDEX(β,ζ)&"|"&INDEX(α,ξ),T(+K2:O5),"")))))

This assumes that the entries in the source table are text, not numeric, just as in the example you give.