3 demension matrix coding - find largest NN elements

I have (M X N X sample) 3-demension matrix, and i want to change all elements to '0' except the largest 'NN' elements

for example;

when the matrix is (4 X 4 X 2) and NN=2

there are two matrix

1 2 3 4
1 2 1 2
2 1 1 2

and

4 1 2 3
1 2 1 2
1 2 2 1

and i want to change into

0 0 3 4
0 0 0 0
0 0 0 0 

and

4 0 0 3
0 0 0 0
0 0 0 0

these two matrix

plz let me know how to change it....

[Walter Roberson]

What do you want to do in the case of duplicates? For example if the original matrix were

1 2 3 4
1 2 1 2
3 1 1 2

then what would you want the output to be for NN=2 ?

[Hakjoon Yoon]

i want

0 0 3 4

0 0 0 0

0 0 0 0

or

0 0 0 4

0 0 0 0

3 0 0 0

only 'NN' elements are needed

Answer 1

[Rik]

You will probably need to loop through the pages. The second output of max should be what you need.

A=rand(4,4,5);
out=A;
element_per_page=size(A, 1)*size(A,2);
for p=1:size(A,3)
    [~,order]=sort(A(:,:,p));
    ind=order(3:end)+element_per_page*(p-1);
    out(ind)=0;
end

(untested code, written on mobile)