Finding the indices of the maximum k elements (even if repeated)

I have an array e.g A=[1 1 0 0 2 0 3 3 0 0] and would like to get the maximum 3 elements (even if repeated ) and their indices

Any help is highly appreciated. Thanks

Answer 1

[Star Strider]

One approach —

A=[1 1 0 0 2 0 3 3 0 0];
[Amax,idxmax] = maxk(A,3)

Amax = 1×3

3 3 2

idxmax = 1×3

7 8 5

See the documentation on maxk (introduced in R2017b) for details.

[rana karem]

Thanks but what if it was 2d matrix e.g --> A=[1 1 0 0 2 ; 0 3 3 0 0]... This wouldn't work

[Star Strider]

Yes, it would!

It just requires a bit of MATLAB programming experience —

A=[1 1 0 0 2 ; 0 3 3 0 0];
[Amax,idxmax] = maxk(A(:),3)                            % Return Values & Linear Indices

Amax = 3×1

3 3 2

idxmax = 3×1

4 6 9

[row,col] = ind2sub(size(A),idxmax);                    % Convert To [row col] Subscripts For Easier REference (Optional)
subscripts = [row col]

subscripts = 3×2

2 2 2 3 1 5

See MATLAB Operators and Special Characters to understand how this works.

[rana karem]

thank you so much

[Star Strider]

As always, my pleasure!