surfc function : plot goes wrong

Hello there,

I am trying to plot my datas with the 'surfc' function, and after struggling and tinking some vectors to give them the good size, I can run my code without any error, but the plots aren't what I excepted (see the photos linked to this post).

This is the code:

ColumnToKeep=7;                                                 
d=dir(fullfile('C:\Users\boulet\Documents\Recherche\2022\,'*.txt'));        % use appropriate wild card name
fnameNew=fullfile('C:\Users\boulet\Documents\Recherche\2022\,'OutputNameOfChoice.txt');
nFiles=numel(d);                                                
for i=1:nFiles
  data=readmatrix(fullfile(d(i).folder,d(i).name));             
  if i==1, OutData=zeros(size(data,1),nFiles);end               
  OutData(:,i)=data(:,ColumnToKeep);                            %Sauvegarder dans la n-ième colonne
end
writematrix(OutData,fnameNew)  
%This first part works extremely well, it creates the 'OutData'file, which
%is a 162x71 double
%%
dataup=OutData(1:81,:);
datadown=OutData(81:161,:);
Vgup=linspace(-40,40,1);
Vgup2=transpose(Vgup);
Vgup3=repmat(Vgup2,81,71);
Vgdown=linspace(40,-40,1);
Vgdown2=transpose(Vgdown);
Vgdown3=repmat(Vgdown2,81,71);
time=0:1:80;
time2=transpose(time);
time3=repelem(time2,1,71);


figure
surfc(time3,Vgup3,dataup);
title('Sweep up','FontSize',20),view([0 0 1]),xlabel('Time (s)','FontSize',20),ylabel('Vg (V)','FontSize',20)
set(gca,'FontSize',16)
shading flat
colorbar('FontSize',16)

figure
surfc(time3,Vgdown3,datadown);
set(gca,'FontSize',16)
shading flat
title('Sweep down','FontSize',20),view([0 0 1]),xlabel('Time (s)','FontSize',20),ylabel('Vg (V)','FontSize',20)
colorbar('FontSize',16)

I can't tell what is wrong ..

If some of you have any advise, I'd be grateful.

Answer 1

[Star Strider]

It would help to have representative data to experiment with.

In its absence, try this —

ylim([39.9 40.1])

Experiment with that approach, for example something like this:

q = 0.1;

ylim(40+[-1 1]*q)

Change (decrease) the value of ‘q’ until you get the desired result.

.

[Ilan Boulet]

Hello,

Thank you for your answer, but the problem is not the y-axis limit. I would like to swap every X and Y axis for each column of Z axis.

[Star Strider]

I do not have the data, and it is difficult to understand what your code does, and to understand what you want to do.

However, assuming that all the surf arguments are equal-sized matrices, simply change the order of the arguments to get the result you want.

[Ilan Boulet]

I am sorry I wasn't clear. I linked the data to this post.

On this data text, there are several columns, each correspond to one measurement. For each of those measurement, I would to associate the whole vector time and the whole vector Vg, it means plot the first column of data in function of time and Vg, then do the same for the second one etc.

I tried to change the order the argument, it changes nothing.

I hope I have been more understandable.

Thank you

[Star Strider]

The various ‘Vg’ vectors do not make sense to me. The ‘Vgup’ variable is a scalar equal to 40 and the ‘Vgdown’ variable is a scalar equal to -40.

I am doing my best to make sense of this. (The ‘OutData’ variable is a (162x71) matrix, and ‘dataup’ here is a (81x71) matrix.)

See if this does what you want —

OutData = readmatrix('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1048790/OutputNameOfChoice.txt');
dataup = OutData(1:81,:);
datadown = OutData(82:end,:);

Vgup=linspace(-40,40,36);
Vgdown=linspace(40,-40,35);
time=0:80;

figure
surf(time, Vgup, dataup(:,1:36).')
xlabel('Time')
ylabel('Vg_{up}')
zlabel('Z')

.