How to Create Multidimensional table in for loop

Trajectory =1:15;
%TrajDetail = zeros(328,4,15);
for i = 1:length(Trajectory)
    
TSPANtf = [ 0      t(i) ] ;
%TSPANtf2 = [ 0      t_corrected_2 ] ;

RelTol = 3.e-14 ; AbsTol = 1.e-16;
Options = odeset('RelTol',3.e-14,'AbsTol',1.e-16);
[tt,xx] = ode113(@(t,x) CRes3BP_xy(t,x,mu),TSPANtf,x0_corrected(i,1:4)',Options);
plot(xx(:,1),xx(:,2),'k',xx(:,1),-xx(:,2),'k')
pause(0.01) ;
  hold on
  axis equal
pos_x = xx(:,1);
pos_y = xx(:,2);
vel_x = xx(:,3);
vel_y = xx(:,4);
TrajDetail (i)= table(pos_x,pos_y,vel_x,vel_y); %here the comes as (see below the italised stuff)
end
% I have not taken the tt values out but still i need

what I wanted to do is get the values of xx and tt for each iteration and store in a table named TrajDetail 1,TrajDetail 2 ...TrajDetail 15.

Note that xx changes the row size according to "tt"

eg: Iteration 1 may cause xx to have 160 x 4 ; Iteration two may have 200 x 4 etc

table should become like Table1 (ieTrajDetail 1) containg

tt;pos_x;pos_y:vel_x;vel_y and has to be done for each iteration

Error for above

Subscripting a table using linear indexing (one subscript) or multidimensional indexing (three or more subscripts) is not supported. Use a row subscript and a variable

subscript.

[Rik]

Tables are 2D in Matlab, containing numbered rows and named columns. If you want something else, you can't use a table. You could use a double array to create a single large multidimensional array, or encapsulate it in a cell array.

Answer 1

[Rik]

A bold guess based on your commented code:

Trajectory =1:15;
TrajDetail = zeros(1,4,15);
for i = 1:length(Trajectory)
    TSPANtf = [ 0      t(i) ] ;
    %TSPANtf2 = [ 0      t_corrected_2 ] ;
    RelTol = 3.e-14 ; AbsTol = 1.e-16;
    Options = odeset('RelTol',3.e-14,'AbsTol',1.e-16);
    [tt,xx] = ode113(@(t,x) CRes3BP_xy(t,x,mu),TSPANtf,x0_corrected(i,1:4)',Options);
    plot(xx(:,1),xx(:,2),'k',xx(:,1),-xx(:,2),'k')
    pause(0.01) ;
    hold on
    axis equal
    TrajDetail (1:size(xx,1),:,i)=xx(:,1:4);
end

[Karthi Ramachandran]

This doesnt wrok I have checked this before posting even

[Rik]

Then the height of xx is not 328. If you share all the variable needed to run this code I can propose an actual fix, for now I'll edit my code to expand the array to the size of xx on the first iteration.

[Karthi Ramachandran]

The variables requiered are t and x0_corrected are attached

[Rik]

Changing the evaluated function to @(t,x) t*x as a placeholder, this runs without error. What is it exactly that makes you conclude it doesn't work for you?

[Karthi Ramachandran]

This works and have tried before submitting original question, I just wanted the output as table format for documentation. I guess its not possible . I retain to classic.

[Rik]

As I mentioned before tables are 2D. Unless you convert your 3D array down to 2D (which is certainly possible to do), you will not be able to store the data as a table.

[Peter Perkins]

Rik is correct but perhaps this needs some more explanation.

Tables contain "variables", which need not be column vectors (that's why they are referred to as "variables" and not as "columns"). So if your data are 3D, NxMxP say, one way to store them is in an NxM table, each variable of which is itself NxP. Or as an NxP table with NxM variables.

Another way to store NxMxP data in a table is by flattening to 2-D as an (N*M)xP table, and then add an extra "indicator variable" to keep track of what 2nd dim slice each row corresponds to.

And finally, if all your data are numeric, just store as an NxMxP numeric matrix.

[Karthi Ramachandran]

Thank you both Rik and Peter.

Answer 2

[Guillaume]

You could store your 15 tables into a cell array,

Trajectory = 1:15;
TrajDetail = cell(size(Trajectory));
for i = 1:numel(Trajectory)  %I recommend using numel instead of length
    %... your code as is
    TrajDetail{i} = table(pos_x,pos_y,vel_x,vel_y);
end

However, you may be better of using just one table with an extra column indicating which iteration the trajectory came from:

Trajectory = 1:15
TrajDetail = [];
for i = 1:numel(Trajectory)
    %... your code as is
    trajindex = repmat(i, size(pos_x, 1), 1);
    TrajDetail = [TrajDetail; table(trajindex, pos_x,pos_y,vel_x,vel_y)]
end

By the way, instead of

pos_x = xx(:,1);
pos_y = xx(:,2);
vel_x = xx(:,3);
vel_y = xx(:,4);
something = table(pos_x,pos_y,vel_x,vel_y);

You could just write:

something = array2table(xx, 'VariableNames', {'pos_x', 'pos_y', 'vel_x', 'vel_y'});

[Karthi Ramachandran]

"All tables in the bracketed expression must have the same variable names." error message ,

[Guillaume]

I assume that error comes from my 2nd example, where I store everything in just one table. I've fixed a typo in the repmat of that code.

You certainly can't get that error from my 1st example.