how to fill with the last non empty value across each column

Hi all, how can I fill the cells in each row with the last non empty or non zero value please? For example : the matrix is [0 9 7 0 0 ; 0 0 0 6 0;0 2 0 0 0; 8 0 4 2 0]; The result shows b=[09700;09760;02760;82420]. Any help is welcomed. Thank you very much.

Answer 1

[Stephen23]

A = [0 9 7 0 0 ; 0 0 0 6 0;0 2 0 0 0; 8 0 4 2 0]
B = A;
for k = 2:size(B,1)
    idx = B(k,:)==0;
    B(k,idx) = B(k-1,idx);
end

Produces this output:

>> A
A =
   0   9   7   0   0
   0   0   0   6   0
   0   2   0   0   0
   8   0   4   2   0
>> B
B =
   0   9   7   0   0
   0   9   7   6   0
   0   2   7   6   0
   8   2   4   2   0

[Qian cao]

Hi, thank you for you answer. It perfectly solved my problem. Can I go on with another question? In the A matrix, how to carry over the last nonempty value until the last nonzero value in each column. So you in second column in A, 2 is the last nonzero value in column 2, so in next round it does not carry over the 2 from the last row. So the output in B should show B(4,2)=0 rather than 2. Thank you again.

[Stephen23]

Run this new code afterwards

idy = true;
for k2 = k:-1:1
    idy = idy & A(k2,:)==0;
    B(k,idy) = 0;
end

to get this:

>> B
B =
   0   9   7   0   0
   0   9   7   6   0
   0   2   7   6   0
   8   0   4   2   0

[Qian cao]

Great! Many thanks.