Remove zeros in a matrix and reduce size

user_5973557 0
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How to remove the zeros in a matrix and reduce its size.

This is my matrix now: enter image description here

I want it to be like this:

745,4.8
740,3
747,11
742,13
746,7.2
741,12.2

Matlab matrix: https://drive.google.com/file/d/1P5h6lhs0O2fxFcxHabAO4hU84UqAZD1m/view?usp=sharing

Can some one give me some tips/pointers on how to do it?

load('matlab_matrix.mat')
L=length(num);
num2=num(4:72,:);
L2=length(num2);
L3=length(num2(1,:));

for i=1:L2;
    for j=1:L3;
        if isnan(num2(i,j)) ~= 1;
            A(i,j)=num2(i,j);
        end     
    end    
end
matrix matlab arrays
2 Answers

Let's define your data:

x = [751 0 0 0
     750 0 0 0
     749 0 0 0
     748 0 0 0
     747 0 11 0
     746 0 0 7.2
     745 4.8 0 0
     744 0 0 0
     743 0 0 0
     742 0 13 0
     741 0 0 12.2
     740 3 0 0
     739 0 0 0];

Then:

ind = find(x(:,2:end));
result = [x(mod(ind-1,size(x,1))+1) x(ind+size(x,1))];

This works even if each row has a different number of nonzeros.

To understand how it works, you may want to take a look at Linear indexing.

user_25869220

It appears that there are unequal number of zeros in each row so just removing zeros doesn't solve the problem. You can use sparse matrix to reduce the size:

result = sparse(num);

If the matrix contains NaNs you can use:

num(isnan(num))=0;
result = sparse(num);
user_65797440
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