How to create a 3-D array using information from FOR loop?

Hi there, I am currently having a problem with trying to get data out from a FOR loop and place into a 3-D array.

I have tried using Array3D= cat(3,A) within and outwith the FOR loop but cant seem to get the array to work.

Thanks

[Matt J]

You should show us your for loop.

[Robert Roy]

Okay, what I am looking for is the different Img values in the 3-D array, after extracting form a specific file.

    Images=20;

    t=19; 

    AvgImg = uint16(zeros(1024,1280));                          

    for

     i=t:Images   
    B=readimx(fullfile(filename,['B000',int2str(i),'.im7'])); 
    C=B.Frames{1}.Components{1}; 
    V = C.Planes;                 
    Img = V{1,1}; 
    AvgImg = AvgImg + Img;            
    end

[Matt J]

Which variable represents the slices that you are trying to concatenate?

[Robert Roy]

Img, it think

Answer 1

[Guillaume]

1. Predeclare the array, 2. Just assign to it using indexing instead of using concatenation that is going to be slow.

Array3D = zeros(1024, 1280, Images); %3D array of 2D images
for i = t:Images
   %read frame, I've not dealt with Davis images for a while but wasn't it 
   %Img = B.Data ?
   Array3D(:, :, i) = Img;
end

[Robert Roy]

Thanks, that gave me the right structure but none of the values out. Davis have updated there stuff so the way I have extracted is the one they suggested. I am just wonder if possible would it be easier if if it was just one row, rather than all the rows?

[Guillaume]

I've just downloaded the latest documentation of readimx, and indeed LaVision have completely changed the way it works.

The code you're using to read the images is fine. Note that I've reproduced your original indexing ( t:Images) which only reads images 19 and 20. Thus Array3D is only going to have values other than 0 for Array3D(:, :, 19) and Array3D(:, :, 20).

Doesn't this work?

nimages = 20;
Array3D = zeros(1024, 1280, nimages);
for imgidx = 1:nimages
   buffer = readimx(fullfile(filename, sprintf('B%05d.im7', imgidx)));
   Array3D(:, :, imgidx) = buffer.Frames{1}.Components{1}.Planes{1};
end

Also note that filename is a misleading variable name for a path. I would have called it path.

Also note the use of sprintf to construct the filename, which will create the right buffer name regardless of the number of digits in the image index.

[Robert Roy]

Thanks very much, yeah I go the answer I need to work, I am just wondering if I am able to take a section from each Img in the loop and plot the pixel intensity radially on a graph with all the Img from the loop.