split a matrix into two matrices according to some rule

How can I generate two separate matrices, one containing the coordinates of line A and the other of line B?

load matrix

figure
plot3(matrix(:,1),matrix(:,2),matrix(:,3),'k.','Markersize',5);
axis equal
grid off

I wanted to try this way but it does not seem the best way.

% range
xRange = [xmin xmax];
yRange = [ymin ymax];
zRange = [zmin zmax];

% indices of points in the range
idx = matrix(:,1) >= xRange(1) & matrix(:,1) <= xRange(2) & ...
    matrix(:,2) >= yRange(1) & matrix(:,2) <= yRange(2) & ...
    matrix(:,3) >= zRange(1) & matrix(:,3) <= zRange(2);

select_matrix = [matrix(idx,1), matrix(idx,2), matrix(idx,3)];

[Stephen23]

Do you have the Image Processing Toolbox installed?

[Alberto Acri]

yes

[Stephen23]

"split a matrix into two matrices according to some rule"

What is the "rule" used to split them up?

[Alberto Acri]

Hi Stephen! sorry, I realised I had not installed 'Image Processing Toolbox'!

[Alberto Acri]

I wanted to know if there is a way to get the subdivision! I don't have any 'rules' at the moment!

Answer 1

[Cris LaPierre]

I would look into clustering. Here is an attempt that uses dbscan, a spectral clustring algorithm included in the Statistics and Machine Learning Toolbox.

You can learn more about this and other clustering techniques in our Practical Data Science with MATLAB specialization on Coursera. It's free to enroll. Here is a link to the video Introdcution to Clustering Algorithms.

https://www.coursera.org/lecture/feature-engineering-matlab/introduction-to-clustering-algorithms-V9PjS

load matrix.mat
% view the raw data
plot3(matrix(:,1),matrix(:,2),matrix(:,3),'k.','Markersize',5);

% use dbscan to identify clusters
idx = dbscan(matrix,1.5,5);
gscatter(matrix(:,1),matrix(:,2),idx)

[Cris LaPierre]

If you know the number of clusters already, use spectralcluster.

load matrix.mat
idx = spectralcluster(matrix,2);
gscatter(matrix(:,1),matrix(:,2),idx)