Index a 2D matrix from a 2D matrix

Hi,

I have a 600x1000 dim 2D matrix and I want to use a nested for loop to index out a 51x51 matrix out of it. How can we do that? It has to be in a nested loop format of--

for ii = 1:1000

for jj = 1:600

...

Thanks.

[Matt J]

Duplicate of

https://www.mathworks.com/matlabcentral/answers/490514-nested-for-loop-for-2d-matrix

Answer 1

[Arash Rabbani]

Well you can simply do this without a loop:

A=rand(600,1000);
B=A(1:51,1:51);

But if you need it to use loops

B=zeros(51);
for ii = 1:51
    for jj = 1:51
    B(ii,jj)=A(ii,jj);
    end
end

[BBB]

Hi,

Thank you for your response!

I actually tried your loop and the other non-loop suggestion, but the moment I put in my data set instead of rand, it gives me an error saying -- " Index in position 1 exceeds array bounds (must not exceed 1)."

So basically, I have to do something like this

for hh = 1:1000
    for pp = 1:600
        b(hh,pp) = lk.*filt;    %lk is the original 600x1000 2D data and filt here is another 2D 51x51 2D matrix that I need to multiply the 51x51 chuncks of data from lk. 
        x_side = hh(lk).*filt;
        y_side = pp(im).*filt;
    end
end 

[Walter Roberson]

Perhaps you should be looking at conv2() ?

[Matt J]

Perhaps you should be looking at conv2() ?

As I also mentioned in your duplicate post here,

https://www.mathworks.com/matlabcentral/answers/490514-nested-for-loop-for-2d-matrix#answer_400986