plot 2D contours

I need help to plot 2D contours as shown in the figure for mutiple files. I am attaching my code and data files for your reference. I am unable to plot it due to some mistake in the code.

navg = 11;
filenames = cell(navg,1);
for i = 1:navg
    filenames = sprintf('queen2_test_%d.dat', i);
    mydata{i}=importdata(filenames);
%     writematrix(avg_mat{i}, filenames{i});
    R = mydata{i}(:,1);%X
    C = mydata{i}(:,2);%Y
    F = mydata{i}(:,7);%F(X,Y)
    figure
    contour(R,C,repmat(F,1,numel(C))');
    grid on;
    end
saveas(gcf,figure,'.png']);

Answer 1

[Ameer Hamza]

Run the attached code with the files you provided

navg = 11;
filenames = cell(navg,1);
for i = 1:navg
    filenames = sprintf('queen2_test_%d.dat', i);
    mydata{i}=importdata(filenames);
    %     writematrix(avg_mat{i}, filenames{i});
    R = mydata{i}(:,1);%X
    C = mydata{i}(:,2);%Y
    F = mydata{i}(:,7);%F(X,Y)
    
    rg = linspace(min(R), max(R), 100);
    cg = linspace(min(C), max(C), 100);
    [Rg, Cg] = meshgrid(rg, cg);
    Fg = griddata(R, C, F, Rg, Cg);
    figure
    ax = axes();
    ax.YDir = 'reverse';
    hold on;
    contourf(Rg,Cg,Fg);
    ax.XAxisLocation = 'top';
    cb = colorbar('Location', 'south');
    cb.Position(2) = cb.Position(2)-0.11;
    grid on;
    saveas(gcf,filenames(1:end-4),'png');
    delete(gcf);
end

[Ameer Hamza]

Note if you are using R2020a, then you can replace the saveas() line to the following line to get a better quality output

exportgraphics(gcf,[filenames(1:end-4),'.png'], 'Resolution', 300);

If you don't have R2020a, then download this package from FEX: https://www.mathworks.com/matlabcentral/fileexchange/23629-export_fig and use the following line to save high-resolution output

export_fig(gcf,[filenames(1:end-4),'.png'], '-r300');

[MS]

Thanks for helping me out. I need a request.

1, I request to flip the x axis an y axis as shown in the figure.

2, contour values as shown in the below figure

[Ameer Hamza]

Run the updated code.

[MS]

Thanks, I want contour also fliped as shwon in the figure. in the updated code, the contour is not flipped.

[Ameer Hamza]

check the updated code.

[MS]

Awesome. I am really grateful to you. The axes is interferrring with the contour as shown in the figure(going inside the contour plot). is it a a bug?

[Ameer Hamza]

This problem is not happening in R2020a. As a quick-fix, you can move the axes a bit up

ax = axes();
ax.YDir = 'reverse';
ax.Position(2) = ax.Position(2)+0.02; % <=== add this line. Tune value of 0.02 until there is no overlap

[MS]

Thank you very much.

[MS]

How to set same maximum and minimum axis for the plot. Please add your inputs.

    caxislimit = 150;
    caxis(obj.hAxes,[-caxislimit caxislimit]);

[Ameer Hamza]

What does that represent? I am not sure why that could be useful. Also, It is impossible in MATLAB. The second limit should be greater than first.

[MS]

Thanks, i want the axis limt eg.,[-100 to 100]. to be same for all the figures to be saved. It will be helpful to compare the intensity between the images. Kindly let me know if you need any calrifications.

[Ameer Hamza]

Oh! I misread it to be caxis(obj.hAxes, [150 150]). Your syntax seems correct. It should show colorbar between -150 to 150.

[MS]

Thanks, i am getting error when i insert the same line in the updated code.

error:

Unable to resolve the name obj.hAxes

[Ameer Hamza]

Are you making a GUI using GUIDE? Where did you get the statement 'obj.hAxes'

[MS]

no, i got it from some gui code. I got the line correct now. Thanks for the help

caxis([-150 150])
colorbar

[Ameer Hamza]

Yes, if you have single axes then you don't need to specify an axes handle.

[MS]

okay. thank you for correcting the mistake.

[MS]

hi ameer,

I want to label the colur bar as shown in the figure1.

my current code is labelling beside as shown in the figure below instead of labelling on the top as shown in the above figure1 .

h = colorbar;
    xlabel(h, 'ω')

Kindly suggest a code.

[MS]

I made the code to change the postion. Thanks.

pos = get(h,'Position');
h.Label.Position = [2 30]; % to change its position
h.Label.Rotation = 0; % to rotate the text