How I can make linked array with matlab?

Recently, I try to make multiple(?) linked array.

for example,

idxA = [1, 2, 3, 4, 5] idxB = [6, 7, 8]

I would like to build new array which can represent linked information between idxB and idxA. idxB elements can linked more than one idxA.

 6|-> 1, 7|->4, 7|->1, 8|->2, 8\->5, 8|->3, ...

Finally, I would like to get array as below

result = [1, [4,1], [2,5,3]]

How I can make it.

I hope that many of you will participate. Thank you.

Answer 1

[Guillaume]

'linked array' does not mean anything in matlab or any language that I know. Maybe you mean linked list, matlab does not have that.

Anyway, your mapping between A and B can be simply defined by a two-column matrix:

link = [6 1
        7 4
        7 1
        8 2
        8 5
        8 3]; %doesn't even have to be ordered

Your result would be have to be a cell array, which you can create any number of ways. The shortest (but maybe not the easiest to understand if you're not familiar with accumarray) would be:

idxB = [6 7 8];
link = [6 1; 7 4; 7 1; 8 2; 8 5; 8 3];

[~, Brow] = ismember(link(:, 1), idxB);
result = accumarray(Brow, link(:, 2), [], @(v) {v'})';
celldisp(result)

Another way, not using accumarray or ismember:

idxB = [6 7 8];
link = [6 1; 7 4; 7 1; 8 2; 8 5; 8 3];

result = cell(size(idxB));
for idx = 1:numel(idxB)
   result{idx} = link(link(:, 1) == idxB(idx), 2)';
end
celldisp(result)

[Heejun Yoo]

Thank you very much for your assistance.