How to make a loop through each row?

Hi! I have a variable A in the size of 50x15000 with different numbers. And I have variable B, the same size 50x15000, that has only zeros and ones. I want to filter the data in the variable A based on variable B, and put the result in variable C. I need to take the numbers from A only if it is zero in the matrix B. One row is one trial in both A and B.

I wrote a small for loop:

C = NaN(size(A));
for i = 1:size(A,1)
    C(i,:) = A(i, B(i,:) == 0);
end

The problem is that, after filtering the data, each row has different number of columns, so it doesn't want to be in one matrix. I have a message like this: "Unable to perform assignment because the size of the left side is 1-by-15000 and the size of the right side is 1-by-13683".

How can I solve this problem?

Thank you!

[Stephen23]

"How can I solve this problem?"

Which would you prefer?:

• a matrix padded with NaN (or some other value).
• a container array (e.g. cell array) of vectors.

[Daria Ivanchenko]

A matrix padded with NaN would be better!

Answer 1

[David Hill]

Make C a cell array

for i = 1:size(A,1)
    C{i} = A(i, B(i,:) == 0);
end

[Daria Ivanchenko]

Yes, this works, thanks, but it is really necessary for me to have all in one matrix and not in differents cells.

[David Hill]

C=zeros(size(A));
C(B==0)=A(B==0);
C(B==1)=nan;