Split an Array in sub-arrays based on the first number in the column

Hello,

I have an array M 2939x4 that I would like to split in sub-arrays based on the number in the first column.

I mean in the first colunm a number is listed, first 0, then 0.02, then 0.04 and so on (with an increment of 0.02) until 2.2, the problem is that the times that this number appear is not always the same (for example the 0 is on the first 28 rows, the 0.02 in the following 24 and the 0.04 in the next 29).

My idea was to find the number of different number listed in the first column (time) and how many times they occurs (b).

[time,b] = unique(M(:,1));

b = [b; length(M)];

How can I continue it?

Thanks in advance.

Answer 1

[Stephen23]

M = [[0;0.2;0.2;0.4;0.6;0.6;0.6],rand(7,3)]

M = 7×4

0 0.4950 0.3418 0.1799 0.2000 0.7419 0.8047 0.6176 0.2000 0.0316 0.7905 0.7259 0.4000 0.0520 0.9471 0.8603 0.6000 0.2431 0.9200 0.8624 0.6000 0.2946 0.9786 0.6720 0.6000 0.1605 0.0039 0.7209

D = diff(find([1;diff(M(:,1));1]));
C = mat2cell(M,D,4)

C = 4×1 cell array
    {[     0 0.4950 0.3418 0.1799]}
    {2×4 double                   }
    {[0.4000 0.0520 0.9471 0.8603]}
    {3×4 double                   }

C{:}

ans = 1×4

0 0.4950 0.3418 0.1799

ans = 2×4

0.2000 0.7419 0.8047 0.6176 0.2000 0.0316 0.7905 0.7259

ans = 1×4

0.4000 0.0520 0.9471 0.8603

ans = 3×4

0.6000 0.2431 0.9200 0.8624 0.6000 0.2946 0.9786 0.6720 0.6000 0.1605 0.0039 0.7209

[Fabio Taccaliti]

Thanks a lot Stephen :)

[Fabio Taccaliti]

What about if I want to plot each last 3 columns of the sub-arrays? column 2 is the x-cooediante, column 3 the y and column 4 the z.

figure(1)

for i = length(C)

hold on; grid on; grid minor; axis equal;

scatter3(C{i}(:,2),C{i}(:,3),C{i}(:,4))

view(3)

xlabel('x [mm]')

ylabel('y [mm]')

zlabel('z [mm]')

end

Something like this, but this plot just the first one

[Stephen23]

for i = 1:numel(C)
        ^^