Probing a plot based on colormap information

How can I probe a plot with colormap data?

As you see, in this case, it only shows the xyz coordinates which is not really useful. I want to be able to see the colormap value (between 0 and 1).

Any ideas? I am using the trisurf function.

Answer 1

[Simon Chan]

Try function datatip & dataTipTextRow if your MATLAB version is after 2019b.

[x,y] = meshgrid(1:15,1:15);
z = peaks(15);
T = delaunay(x,y);
s = trisurf(T,x,y,z);
dt = datatip(s);
s.DataTipTemplate.DataTipRows(end+1) = dataTipTextRow('Colormap Value',T,'%.1f');

[Pelajar UM]

Thanks, but I get the following error:

Error using matlab.graphics.datatip.DataTipTemplate/set.DataTipRows
Value must be compatible with the data source.

In my code, "flow12" has the same dimensions as F. I think (?) this is the problem. Basically I have a value assigned to each face, rather than each vertex.

s = trisurf(F,P(:,1),P(:,2),P(:,3), flow12, 'Parent', app.UIAxes2_10);
c = colorbar(app.UIAxes2_10);
caxis(app.UIAxes2_10,[0.333 1]);
colormap(app.UIAxes2_10, jet);
c.Label.String = 'T11 Tensor';
dt = datatip (s);
s.DataTipTemplate.DataTipRows (end+1) = dataTipTextRow ('T11', flow12,'%.1f');

[Simon Chan]

Try the following:

s.DataTipTemplate.DataTipRows (end+1) = dataTipTextRow ('T11', s.CData,'%.3f');

[Pelajar UM]

Same error unfortunately. :(

[Simon Chan]

Could you please try once more.

clear; clc;
[x,y] = meshgrid(1:15,1:15);
z = peaks(15);
T = delaunay(x,y);
C = rand(size(T,1),1);                  % Color based on number of faces
s = trisurf(T,x,y,z,C);
axis equal;
c = colorbar;
caxis([0.333 1]);
colormap(jet);
c.Label.String = 'T11 Tensor';
dt = datatip(s);
s.DataTipTemplate.DataTipRows(end+1) = dataTipTextRow('Colormap Value',repmat(s.CData,1,3),'%.3f');

Mainly this one:

s.DataTipTemplate.DataTipRows (end+1) = dataTipTextRow ('T11', repmat(s.CData,1,3),'%.3f');

[Pelajar UM]

This works perfectly. Thank you so much! One minor issue is that when I run the code, it has already selected a point and showing the data tip before I even interact with the model. Can this be fixed?

[Simon Chan]

Add one more line:

s.DataTipTemplate.DataTipRows(end+1) = dataTipTextRow('Colormap Value',repmat(s.CData,1,3),'%.3f');
delete(dt);         % Add this in the last line

or right click on the figure to delete current data tip

[Pelajar UM]

Wonderful! Now is it possible to remove X,Y,Z and only keep the colormap value?

[Simon Chan]

Add another line :-)

s.DataTipTemplate.DataTipRows(end+1) = dataTipTextRow('Colormap Value',repmat(s.CData,1,3),'%.3f');
s.DataTipTemplate.DataTipRows(1:3)=[];      % Add this line as well
delete(dt);

[Pelajar UM]

Looks great now. Thank you again!

Answer 2

[KSSV]

I don't think you would be able to see the values like that. But you can see what value it has using:

F = scatteredInterpolant(x,y,z,c) ;
ci = F(xi,yi,zi) ;  % where xi, yi, zi is the picked point 

[Pelajar UM]

Thanks. Can I at least output the (xi,yi,zi) values from the probe? ... as in when the user clicks on a point, and not manually entering the coordinates.

[KSSV]

Yes you can. REad about this:

https://in.mathworks.com/matlabcentral/answers/38631-multiple-datatip-value-extraction

[Pelajar UM]

I'm getting an error:

d = datacursormode(app.UIAxes2_10);

Error using datacursormode 
Invalid figure handle

[Simon Chan]

Choose figure object

f = figure;
ax = gca;
d = datacursormode(f)

d = 
  DataCursorManager with properties:

        SnapToDataVertex: on
            DisplayStyle: 'datatip'
    DefaultExportVarName: 'cursor_info'
             Interpreter: 'tex'
               UpdateFcn: []
                  Enable: off
                  Figure: [1×1 Figure]

d2 = datacursormode(ax)

Error using datacursormode (line 154)
Invalid figure handle

[Pelajar UM]

Thanks, but how do you get the figure object of an UIAxes in app designer?

trisurf(F,P(:,1),P(:,2),P(:,3), flow12, 'Parent', app.UIAxes2_10);
            c = colorbar(app.UIAxes2_10);
            caxis(app.UIAxes2_10,[0.333 1]);
            colormap(app.UIAxes2_10, jet);
            c.Label.String = 'T11 Tensor';

On another note, there seems to be a way to modify the data tip function, but I don't really know how to implement customized functions in app designer:

https://www.mathworks.com/matlabcentral/answers/339066-how-to-data-cursor-displaying-colorbar-value