how to use for loop to compute a matrix

Hello. I'm a beginner at Matlab.

I want to use for loop.

I got data (25 x 12852) using this code.

I want to concatenate the matrix (dist).

For example, the last part of whole code,

dist = dtw(data(:,1),data(:,2));
dist = dtw(data(:,2),data(:,3));
dist = dtw(data(:,3),data(:,4));
dist = dtw(data(:,4),data(:,5));
dist = dtw(data(:,5),data(:,6));
......
dist = dtw(data(:,12851),data(:,12852));

Finally, I want to get one matrix.

Can I get an idea to solve this?

Also, is it resonalble to use dynamic time warping (DTW) for video classification?

clear all
close all
%// read the video:
list = dir('*.avi')
% loop through the filenames in the list
for k = 1:length(list)
    reader = VideoReader(list(k).name);
    vid = {};
    while hasFrame(reader)
        vid{end+1} = readFrame(reader);
    end
    %// estimate foreground as deviation from estimated background:
    cellSize = [8 8];
    for i=1:25
        fIdx(i) = i; %// do it for frame 1 ~ 60
        frameGray{i} = vid{fIdx(i)};
        [featureVector{i},hogVisualization{i}] = extractHOGFeatures(frameGray{i},'CellSize',cellSize);
    end
    data = cell2mat(featureVector');
    data = double(data);
    
    dist = dtw(data(:,5),data(:,6));
end

Answer 1

[Sindar]

Assuming each one produces a 25 x 12852 dist array, you can do this fairly easily. Which dimension do you want to concatenate on?

This solution adds each one as a new "page" (3rd dimension)

clear all
close all
%// read the video:
list = dir('*.avi')
% preallocate dist
dist = zeros(25,12852,length(list));
% loop through the filenames in the list
for k = 1:length(list)
    ...    
    dist(:,:,k) = dtw(data(:,5),data(:,6));
end

If you want to concatenate on rows:

dist = zeros(25*length(list),12852);
...
    dist((1:25)+25*(k-1),:) = dtw(data(:,5),data(:,6));

or columns:

dist = zeros(25,12852*length(list));
...
    dist(:,(1:12852)+12852*(k-1)) = dtw(data(:,5),data(:,6));

[Sindar]

Looking back at your code, it seems dist might be a different size, and you may want a second loop over the size of data. Hopefully my answer still helps