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

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Fabio Taccaliti
Fabio Taccaliti 2022-4-19
评论： Stephen23 2022-4-20
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.

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Stephen23
Stephen23 2022-4-19
Ran in:
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
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Fabio Taccaliti
Fabio Taccaliti 2022-4-19
编辑：Fabio Taccaliti 2022-4-19
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

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