Different commands for strutures and "regular" matrices

I have problems using structures in some commands. I am not able to do the same things with structures as with regular matrices.

Example: I have a "regular" 11x8x6 matrix called gjG. When I write "gjG(11,:,:)", Matlab returns row 11 for the 6 different 11x8 matrices. I have constructed a 1x6 structure gjG that contains the same 6 11x8 matrices as above. When i write "gjG(:).Data(11,:)", Matlab gives the following message: "Scalar index required for this type of multi-level indexing." Does anybody know how I can get around this? This prevents me from making figures in a loop I have written that works only when I use "regular" matrices.

I think the probelm lays in the ":" after "gjG". If I writhe a number between 1 and 6, it works. Also if i only write gjG(:).Data it works. The problem is that in my figure loop I need something that works as if "gjG(:).Data(11,:)" works.

[Azzi Abdelmalek]

give a short numeric example of your struct variable

Answer 1

[Matt J]

Since you're looping, I don't quite understand why you don't loop over gjG(i).Data(11,:) letting i=1...6 individually in the loop.

Failing that, you've chosen an awkward data organization for the kind of manipulations you want to do. The only thing you can really do is convert back to numeric array form,

 tmp = cat(3,gjG(:).Data)

 tmp(11,:,:),

[Karl]

The second thing you suggested worked, but I want to avoid construting new matrices.

The first thing also works when I plot a graph, but I want to switch axis. Now I get 6 different lines and 8 points on the x-axis. Remember that the structure is 6 11x8 matrices. Instead I want 8 lines with 6 points on the x-axsis. How do I do that?

My loop looks like this now:

Alder = {'<20', '2029','3039','4049','5059','6069','>70', 'all'};
Aar = {'2011', '2012', '2013_1', '2014_1', '2014_s2', '2014_s5'};

nAar = length(Aar);

numberOfColors = nAar; 
myColorMap = lines(numberOfColors);  

figure
hold on
for iAar = 1:nAar
  plot(gjG(iAar).Data(11,:), 'color', myColorMap((iAar), :));
set(gca, 'XTickLabel',Alder)
legend((Aar),'location','NE','FontSize',10);
end
hold off

[Matt J]

The second thing you suggested worked, but I want to avoid construting new matrices.

I doubt it's worth it. Any data small enough to plot is small enough to copy. The only other way to do the new things you want is using a nested for-loop:

pline=zeros(1,6);

hold on

for j = 1:8
  for i=1:6

      pline(i)=gjG(i).Data(11,j);

    end

    plot(pline, 'color', myColorMap((iAar), :));
  set(gca, 'XTickLabel',Alder)

    legend((Aar),'location','NE','FontSize',10);

end
hold off

What is the motivation for holding this as a struct ARRAY? What are the other struct fields and their dimensions? If they're all the same, you could combine your data into the fields of a scalar struct. and do things like

    for j=1:8
      plot(gjG.Data(11,i,:), 'color', myColorMap((iAar), :));
    end

    for i=1:6
      plot(gjG.Data(11,:,i), 'color', myColorMap((iAar), :));
    end

Answer 2

[Daniel Shub]

Maybe a function like

myfun = @(x, ii)subsref(reshape([x(:).Data], size(x(1).Data, 1), size(x(1).Data, 2), length(x)), struct('type', '()', 'subs', {{ii, ':', ':'}}))

This anonymous function is not very general and if you deviate from the expected inputs bad things will happen ...

To see how it works, first create some dummy data

[gjG(1:6).Data] = deal(randn(11, 8), randn(11, 8), randn(11, 8), randn(11, 8), randn(11, 8), randn(11, 8));

Then call it

myfun(gjG, 11)

Answer 3

[Andrei Bobrov]

out = arrayfun(@(x)gjG(x).Data(11,:),(1:numel(gjG))','un',0);