Getting the max value of a certain column, fetching the entire row from a 3D matrix and write those in a new matrix

Hi,

I have a 3D matrix Once_Still_3D of form 68 x 8 x 30, with 30 being the timesteps. I need to find the max value of column 3 from each timestep, fetch the corresponding row and put the row in a new matrix where the row index is same as the timestep index of the 3D matrix.

for k=1:30
    [~,idx]=max(Once_Still_3D(:,3,k));
    Out(k,:)=Once_Still_3D(idx,:,k);
end

Using this code results in repetition of values found with k=1 in the output file Out.

Here's the output:

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

113.500000000000 68 0.172359450012208 0.0262343597381685 0 0 0 0

Kindly help.

[Sindar]

To me, this looks like it should work. I'd check your data. Does Once_Still_3D(:,3,1) look different from Once_Still_3D(:,3,2)?

[Arup Bhattacharya]

Yes, matrices for all the timesteps are different. I am also trying to figure this out whether there is a problem with the 3D matrix or whether the max values everywhere is same.

Answer 1

[KSSV]

A = rand(68,8,30) ;   % randmom data for demo 
col = 3 ;    % third column from which max to be seeked 
[m,n,p]  =size(A) ;   % dimensions 
iwant = zeros(p,n) ;   % initialze the required 
for i = 1:p
  [val,id] = max(A(:,3,i)) ; 
  iwant(i,:) = A(id,:,i) ; 
end

[Sindar]

How is this different from their code?