How can I obtain a certain value from the function 'find' from a 3x2 cell?

I need a certain variable "a" to be equal to either 1,2 or 3 according to two previous selection "Firstselection" and "Secondselection" which algo go from 1 to 3.

I have a 3x2 cell Comb = [1,2; 2,3; 1,3]. I have to assign "a" to a find function so that when Firstselection = 1 & Secondselection = 2 (and viceversa), a = 1, Firstselection = 2 & Secondselection = 3 (and viceversa), a = 2 and Firstselection = 1 & Secondselection = 3 (and viceversa), a = 3, all based on the cell Comb. I already solved it with an if cycle but now I need to apply the function find to the cell to obtain a certain value of "a" according to my 2 selections. I cannot change the cell.

[Stephen23]

"I have a 3x2 cell Comb = [1,2; 2,3; 1,3]."

What you show is not a cell array, but a simple numeric matrix.

Do you actually have a cell array (as you write) or a numeric matrix (as you show)?

[Pietro Fedrizzi]

Sorry, my mistake... Comb is indeed a cell array:

{[1]} {[2]}

{[2]} {[3]}

{[1]} {[3]}

[KSSV]

You can convert it o matrix using cell2mat and then use find.

[Pietro Fedrizzi]

I previously tried that. I know that I can obtain a matrix, but the problem is that I don't know how to apply find to either the cell or the matrix in order to obtain my goal...

[dpb]

It's not clear to me what the desired result is, sorry.

Show us the input and then the expected output...

[Pietro Fedrizzi]

Firstselection = 1 | 2 | 3; %identified by a numeric slider

Secondselection = 1 | 2 | 3;

Comb = {1,2;2,3;1,3};

Comb = 3×2 cell

% 'a' has to be either 1,2,3 according to my selection as I said previously.

% (Firstselection =1 & Secondselection =2 (and viceversa) -> a = 1, and so on...

% Is there a way to obtain that using the find

% function?

[dpb]

Just repeating the same unclear verbiage doesn't help -- SHOW us the input and corresponding output expected.

Answer 1

[Dave B]

I think you're asking how to search for the index of a row in a matrix based on multiple columns (although you have a cell array, you can just convert that to start).

You'll want to think about a few 'special' cases: what if it isn't found? What if it's found in more than one place? ismember does a nice job if you're not concerned with the multiple result issue:

comb={1,2;3,4;1,3};
comb_mat=cell2mat(comb);

target=[1 2];
[~,wherefound]=ismember(target,comb_mat,'rows')

wherefound = 1

target=[3 4];
[~,wherefound]=ismember(target,comb_mat,'rows')

wherefound = 2

target=[1 3];
[~,wherefound]=ismember(target,comb_mat,'rows')

wherefound = 3

target=[12 13];
[~,wherefound]=ismember(target,comb_mat,'rows') % wherefound will be 0 if not found

wherefound = 0

comb={1,2;3,4;1,3;1,2};
comb_mat=cell2mat(comb);

target=[1 2];
[~,wherefound]=ismember(target,comb_mat,'rows') % wherefound will be the first index if multiple occurrences

wherefound = 1

Otherwise you can combine find with an &:

comb={1,2;3,4;1,3};
comb_mat=cell2mat(comb);

target=[1 2];
find(comb_mat(:,1)==target(1) & comb_mat(:,2)==target(2))

ans = 1

target=[3 4];
find(comb_mat(:,1)==target(1) & comb_mat(:,2)==target(2))

ans = 2

target=[1 3];
find(comb_mat(:,1)==target(1) & comb_mat(:,2)==target(2))

ans = 3

target=[12 13];
find(comb_mat(:,1)==target(1) & comb_mat(:,2)==target(2)) % find will return empty if not found

ans =

  0×1 empty double column vector

comb={1,2;3,4;1,3;1,2};
comb_mat=cell2mat(comb);

target=[1 2];
find(comb_mat(:,1)==target(1) & comb_mat(:,2)==target(2)) % find will return both indices if multiple results are found

ans = 2×1

1 4

[Pietro Fedrizzi]

Thank you very much! This example works great with my code, for the only exception that in my work 'target' is an array that I can decide, so it works just fine.

Thank you again for your time and your help!