MATLAB: For 1:x with unkonw x

arrayforfor loopMATLAB

Hi everybody,
i have an array like this:
ARRAY
X Y Z C
-3 4 5 1
5 6 2 2
4 4 9 1
6 6 7 2
4 6 2 3
9 9 7 3
where C goes from 1 to x (x unknow). I want to create a for to have x arrays with XYZ associated with C, like this:
for k=1:x
A(1:k)=[ARRAY(:,1),ARRAY(:,2),ARRAY(:,3),ARRAY(:,4)==1:k]
end
A1
X Y Z
-3 4 5
4 4 9
A2
X Y Z
5 6 2
6 6 7
A3
X Y Z
4 6 2
9 9 7
Thank you!

Best Answer

Don't think of naming variables dynamically (https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval ) use cell instead:
a=[-3  4  5  1
5  6  2   2
4  4  9   1
6  6  7   2
4  6  2   3
9  9  7   3];
u=unique(a(:,4));
A=cell(1,numel(u));
for i = 1:numel(u)
      idx = (a(:,4) == u(i)); % edited after Jan's comment
%     idx=ismember(a(:,4),u(i));
    A{i}=a(idx,1:3);
end
celldisp(A)
Gives:
A{1} =
 
    -3     4     5
     4     4     9
 
A{2} =
 
     5     6     2
     6     6     7
 
A{3} =
 
     4     6     2
     9     9     7
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