## How to Overwrite Data

Asked by Nikolaos Zafirakis

### Nikolaos Zafirakis (view profile)

on 8 Jul 2019
Latest activity Edited by Stephen Cobeldick

### Stephen Cobeldick (view profile)

on 8 Jul 2019
Accepted Answer by Stephen Cobeldick

### Stephen Cobeldick (view profile)

The main objective is to overwrite the maximum values in matrix B with the values collected in matrix A
So I have:
A = (1:100,1) % A is the matrix with the results I need. So, A(1,1) = 4 , A(6,1) = 9
B = (1:100,1:2) % B always contains on each row a 0 and a value. Such as B(1,1:2) = 0 2 , B(6,1:2) = 53 0.
% Result would be for:
% C = (1:100,1:2) you would get C(1,1:2) = 0 4 , C(6,1:2) = 9 0

### madhan ravi (view profile)

on 8 Jul 2019
not clear , illustrate with a short example
Stephen Cobeldick

### Stephen Cobeldick (view profile)

on 8 Jul 2019
@Nikolaos Zafirakis: whatever you do, do NOT use loops for this! Using loops would be a waste of MATLAB's efficient code vectorization abilities:

### Tags ### Stephen Cobeldick (view profile)

Answer by Stephen Cobeldick

### Stephen Cobeldick (view profile)

on 8 Jul 2019
Edited by Stephen Cobeldick

### Stephen Cobeldick (view profile)

on 8 Jul 2019

One simple MATLAB way:
C = max(A,B).*(B~=0)
Or for MATLAB versions prior to R2016b:
C = bsxfun(@max,A,B).*(B~=0)

Answer by Abhishek Kumar

### Abhishek Kumar (view profile)

on 8 Jul 2019

for i= 1:100
if B(i, 1) == 0
B(i, 1)= A(i, 1);
elseif B(i, 2) == 0
B(i, 2) = A(i, 1);
end
end
The above bit of code should give you the desired output

Answer by Shameer Parmar

### Shameer Parmar (view profile)

on 8 Jul 2019

Here you go..
A = [1; 5; 7; 9; 4; 6; 8; 2; 3];
B = [4 0; 5 6; 8 0; 7 5; 0 8; 4 9; 5 6; 0 1; 2 8];
C = B;
for i = 1:length(B)
if B(i,1) == 0
C(i,2)= A(i,1);
elseif B(i,2) == 0
C(i,1)= A(i,1);
end
end