Unnest two columns in google sheet

Question

I have a table like this one here (basically it's data from a google form with multiple choice answers in column A and B and non-muliple choice data in column C) I need a separate row for each multiple choice answer.

Column A	Column B	Email
A,B	XX,YY	1@gmail.com
A,C	FF,DD	2@gmail.com

I tried to un-nest the first column and keep the remaining columns like this

enter image description here

I tried several approaches I found with flatten and split with array formulas but I don't know where to start really.

Any help or hint would be much appreciated!

Answer 1

You can use the split function on the column A and after that, use the index function. Considering the table, you can use:

=index(split(A2,","),1,1)

The split function separate the text using the delimiter indicated, returning an array with 1 line and 2 columns; the index function will return the first line and the first column from this array. To return the second element from the column A, just change to

=index(split(A2,","),1,2)

Answer 2

I think there's no easy solution for this. You're asking for as many combinations of elements as multiple-choice elections have been made. Any function in Google Sheets has its potentials and limitations about how many elements it can express. One very useful formula here is REDUCE. With REDUCE and sequences of elements separated by commas counted with COUNTA, you can stablish this formula:

=QUERY(REDUCE({"Col A","Col B","Email"},SEQUENCE(COUNTA(A2:A)),LAMBDA(z,c,{z;LAMBDA(ax,bx,
REDUCE({"","",""},SEQUENCE(ax),LAMBDA(w,a,
{w;
REDUCE({"","",""},SEQUENCE(bx),LAMBDA(y,b,
{y;INDEX(SPLIT(INDEX(A2:A,c),","),,a),INDEX(SPLIT(INDEX(B2:B,c),","),,b),INDEX(C2:C,c)}
))})))
(COUNTA(SPLIT(INDEX(A2:A,c),",")),COUNTA(SPLIT(INDEX(B2:B,c),",")))})),
"Where Col1 is not null",1)

Since I had to use a "initial value" in every REDUCE, I then used QUERY to filter the empty values: