Creating a nested loop

Suppose I want to generate a 2 x 9 matrix by looping the following code twice

for j = 1:size(Mdl_vol,2)

EstMdl = estimate(Mdl_vol(j),IVOLI(:,1),'Display','off');

results = summarize(EstMdl);

AIC(j) = results.AIC;

BIC(j) = results.BIC;

end

I tried this;

for i = 3:4

for j = 1:size(Mdl_vol,2)

EstMdl = estimate(Mdl_vol(j),IVOLI(:,i),'Display','off');

results = summarize(EstMdl);

AIC(i,j) = results.AIC;

BIC(i,j) = results.BIC;

end

end

but it gives me a 4x9 matrix for some reason

Answer 1

[Voss]

The resulting matrices have 4 rows because i goes from 3 to 4 and you use i as the row index when building the matrices.

To have the 3rd and 4th columns of IVOLI correspond to rows 1 and 2 of AIC and BIC, you can do this:

n_col = size(Mdl_vol,2);
AIC = zeros(2,n_col); % initialize the matrices to the right size
BIC = zeros(2,n_col);
for i = 3:4
    for j = 1:n_col
        EstMdl  = estimate(Mdl_vol(j),IVOLI(:,i),'Display','off');
        results = summarize(EstMdl);
        AIC(i-2,j) = results.AIC;
        BIC(i-2,j) = results.BIC;
    end
end

Or you can do this, which is more general:

I_col_idx = [3 4];
n_row = numel(I_col_idx);
n_col = size(Mdl_vol,2);
AIC = zeros(n_row,n_col); % initialize the matrices to the right size
BIC = zeros(n_row,n_col);
for i = 1:n_row
    for j = 1:n_col
        EstMdl  = estimate(Mdl_vol(j),IVOLI(:,I_col_idx(i)),'Display','off');
        results = summarize(EstMdl);
        AIC(i,j) = results.AIC;
        BIC(i,j) = results.BIC;
    end
end