Rearrange a given array

Given a vector

V = [ 19 15 11 2 16 3 1 18 14 3 18 19 20 1 13 4 14 3 1 2 16 4 3 1 19 3 20 4 13 1 15 2 18 4 1 20 19 17 3 1 13 20 3 4 17 18 19 20 14 15 11 2]

I would like to rearrange V in this way.

every 10 element I want to collect the elements that are in the same column of A

A=      [0  15 11 2 4  0  3 1 13;
        14  0 16 0 0  0  0 0 0;
        0   0 0  0 8  0  0 0 0;
        0   0 18 0 0  0  0 0 0;
        0   0 19 0 0  0  0 0 0;
        0   0 0  0 0  0  0 0 0];
   

In this case, we want to collect 11,16,18,19 and also 4,8. Doesn't mind for the others that are just one in the columns, but if we have the same number I want to collect this two number together (see below with 3)

So for example, for the first 10 elements:

        19 15 11 2 16 3 1 18 14 3 
        
        

they will be rearrange as

        19 11 16 18 15 2 3 3 1 14 
        

Answer 1

[Guillaume]

This would work as long as V has a multiple of 10 elements:

%demo data
V = [ 19 15 11 2 16 3 1 18 14 3 18 19 20 1 13 4 14 3 1 2 16 4 3 1 19 3 20 4 13 1 15 2 18 4 1 20 19 17 3 1 13 20 3 4 17 18 19 20 14 15];
A=      [0  15 11 2 4  0  3 1 13;
        14  0 16 0 0  0  0 0 0;
        0   0 0  0 8  0  0 0 0;
        0   0 18 0 0  0  0 0 0;
        0   0 19 0 0  0  0 0 0;
        0   0 0  0 0  0  0 0 0];
    
assert(mod(numel(V), 10) == 0, 'V length is not a multiple of 10');
V10 = reshape(V, 10, []);  %rearrange V in batches of 10
[~, where] = ismember(V10, A);  %find location of elements in A
[~, col] = ind2sub(size(A), where);  %convert location into column index
[~, order] = sort(col, 1);  %and sort by column order
newV = reshape(V10(order + (0:size(order, 1):numel(order)-1)), 1, [])  %and rearrange columns of V10 according to that order

Note that elements of V not found in A get reordered first in each group of 10.

[luca]

if the length of V is not a multiple of 10. Is there a way to stop before 10 and close the vector without matlab gives error?

thanks

[luca]

Do you have a solution?

[Guillaume]

If you expect instantaneous answers, then this forum is not for you. We help in our own time.

If the length of V is not a multiple of 10, the simplest may be to pad it with NaN:

V = [V, NaN(1, mod(-numel(V), 10))];
%... code as above
newV = V(1:numel(V)) %to remove the added NaN (which will always be sorted to the end)

[luca]

Sorry Guillaume,

I didn't want to rush you! Pardon me and thanks for your help!

[luca]

The fact to insert NaN complicate and create confusion once we have to reorder. If you have other suggestion on how to do it, please let me know!

Thanks

[Guillaume]

Oh, yes, forgot I'm not sorting the numbers but their column position (which is 0 for NaNs).

newV = V(~isnan(V))

for the last line. The rest as before.

[luca]

thanks again for your time