MATLAB: How to extract values from a field of a stucture

strucure- handling fields

Hi everyone, I state that I'm a beginner in the use of Matlab, so I guess that what I'm asking could be solved quite easily, but I have been reading and trying a lot of different ways and still, I have no solutions. I have a structure ("Dati"), which is generated by an external software that works on a geographic grid. This grid has 196 cells in the X direction, and 337 in the Y direction; On this grid 244 different scenarios have been launched.

By writing "A=extractfield(Dati,'Val') I get, of course, the list of all the data inside the structure, and by "plot(extractfield(Dati,'X'),extractfield(Dati,'Y'))" I can represent the grid; but what I would like is to get the chance to represent in a plot the grid with all the different scenarios (244), and be able to handle the value of the third variable (energy per transport) in order to later calculate an average. Can someone help me?

Best Answer

I don't have the data so I cannot test it. Try

% select the Scenario
iScenario = 1;
% plot
surf(Dati.X,Dati.Y,Dati.Val(iScenario,:,:));

Note that the field Val has different dimensions from X and Y, so the previous code doesn't work. But maybe you have more insight on the original data

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MATLAB: How to plot a surface from x and y having different values of z, i.e. (x,z1) and (y,z2)

Insufficient information to draw a "surface".

You have essentially marginal data, in the sense of a marginal distribution. So for each point, you have x and z, or y and z.

But a surface requires that for ANY combination of x AND y, you can produce a value of z. So for any point in the first set, you know what value of x produced a value z. But you provide no information about the y that was used, even if only implicitly. So all the y data is missing there. The same applies to the second set. x is completely missing.

So, sorry, but you have insufficient information to generate the surface between those axes. It could do anything you wish to imagine for some combination of both x and y. But since there is no hint as to what it does do, you are stuck. You cannot infer a complete surface.

MATLAB: How to plot z (data) on x-y (grid) from a structure

I took a few liberties with your code since I do not have the Mapping Toolbox.

Try this:

TotalData = load('Etransp_5steps.mat');
X = TotalData.data.X;
Y = TotalData.data.Y;
Values = TotalData.data.Val;
%% 

CumHours=[0.3;    3.03;   14.56;  3.34;   0.3;]; %5 amount of hours for every simulation
sumCH=sum(CumHours(:));
s=1;
f=5;
for cont=1:f
        NewVal(s,:,:)=Values(s,:,:)*CumHours(s,1);
    s=1+s;
end
%% 
j=1;
Cum=NewVal(j,:,:);
while j<f
    j=j+1;
    Cum=Cum+NewVal(j,:,:);
end    
TOT=Cum;    
ResultVal=TOT(1,:,:)/sumCH;
figure(1);
s=plot3(X(2:end,2:end),Y(2:end,2:end),squeeze(ResultVal(1,:,:)));
figure(2);
hs = surf(X(2:end,2:end),Y(2:end,2:end),squeeze(ResultVal(1,:,:)))
grid on
hs.EdgeColor = 'none';
view(-20,40)

producing this figure(2):

Although this might be what you want:

figure(3)
[~,hc] = contourf(X(2:end,2:end),Y(2:end,2:end),squeeze(ResultVal(1,:,:)),50);
hc.LineStyle = 'none';
colormap(jet)

producing:

Experiment to get the result you want.

Best Answer

Related Solutions

MATLAB: How to plot a surface from x and y having different values of z, i.e. (x,z1) and (y,z2)

MATLAB: How to plot z (data) on x-y (grid) from a structure

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