Can sfit objects be plotted to specific axis in GUI (not a figure window)?

Hi,

I have been given a code that fits a surface to a 3D data set. My task is to add it to an existing GUI, that I have developed using App Designer in Matlab R2020a.

            X=1:10;  %Made-up data
            Y=1:10;
            Z=1:10;
            
            n=(1:length(Z));
                     
            Ztop=(max(Z)+10).*ones(1,length(n));
            plot3(app.Map, X(n),Y(n),Ztop,'.k','markersize',12); %plot datapoints
            
            hold(app.Map, 'on')
            
            options = fitoptions('Method','BiharmonicInterpolant');
            [sf,gof] = fit([X', Y'],Z','biharmonicinterp',options); %create sfit obj
            
            axis(app.Map,'equal')
            caxis(app.Map,'auto')
            %caxis([0 maxV]) ;
            colormap(app.Map);
            
            plot(app.Map, sf); %plot fitted surface - THAT'S THE ISSUE, IT WORKS UNTIL THIS LINE!
            %shading interp
            colorbar(app.Map);
            %view(2)
            
            hold(app.Map, 'off')

The code works just fine in a figure window but, when I try to display the output to a graphic axis (app.Map) integrated in the GUI, I get the following:

Error using plot

Data must be numeric, datetime, duration or an array convertible to double.

I read the help for plot() and it seems that plot(ax,_) is the right format. However, I also tried another common format, just in case:

H = plot(sf, 'Parent', app.Map )

This returns a long list of errors. At this point, I think I need some guidance.

Thank you!

PS: one work-around might be plotting to a figure window, set with visibility 'off'. Then export the result to jpg and display it with imshow inside the GUI. But I would still like to know what I am doing wrong, if possible.

Answer 1

[Giorgio Menallo]

This is the solution:

            X=[wL,wIN1,wIN2,wIN3,wIN1,wIN2,wIN3,wR,wL,wIN1,wIN2,wIN3,wR];
            Y=[hIN,hB,hB,hB,hIN,hIN,hIN,hIN,hBC,hBC,hBC,hBC,hBC];
            Z=[lL,lB1,lB2,lB3,lIN1,lIN2,lIN3,lR,BC1,BC2,BC3,BC4,BC5];
            
            n=(1:length(Z));
            Ztop=(max(Z)+10).*ones(1,length(n));
            plot3(app.Map, X(n),Y(n),Ztop,'.k','markersize',12)
            view(app.Map, 2)
           
            hold(app.Map, 'on')
            
            [x y] = meshgrid([min(X):1:max(X)],[min(Y):1:max(Y)]);
            options = fitoptions('Method','BiharmonicInterpolant');
            sf = fit([X',Y'],Z','biharmonicinterp',options);
            z = sf(x,y);
            surf(x,y,z,'Parent', app.Map,'FaceColor','interp', 'EdgeColor','None')
            axis(app.Map, 'equal')
            caxis(app.Map, 'auto')
            app.Map.YLim = [hB hBC];
            app.Map.XLim = [wL wR];
            view(app.Map, 2)
            colormap(app.Map);
            colorbar(app.Map);
            
            hold(app.Map, 'off')

Answer 2

[Geoff Hayes]

Giorgio - from Plot cfit or sfit object, the code to plot the sf object would be

plot(sf, 'Parent', app.Map)

. When you try to plot as

plot(app.Map, sf);

then you are calling the 2-D line plot function.

[Giorgio Menallo]

I see.

But I tried that and it returns soooo many errors.

Especially the first warning (Input #2 expected to be a cell array, was double instead) makes no sense to me.

Warning: The following error was caught while executing 'curvefit.gui.FunctionSurface' class destructor:
Error using cellfun
Input #2 expected to be a cell array, was double instead.

Error in curvefit.gui.FunctionSurface/delete (line 160)
            cellfun( @delete, obj.SurfaceListeners );

Error in curvefit.gui.FunctionSurface (line 78)
            narginchk( 1, 1 );

Error in sfit/plot>iPlotSurface (line 96)
hFS = curvefit.gui.FunctionSurface( hParent );

Error in sfit/plot (line 52)
        h1 = iPlotSurface( hParent, obj ); 
Error using event.proplistener
While adding a PostSet listener, property 'XLim' in class 'matlab.ui.control.UIAxes' is not defined to be SetObservable.

Error in curvefit.proplistener>iCreateEventListener (line 43)
listener = event.proplistener( Source, property, 'PostSet', Callback );

Error in makeListener (line 42)
    listener = Factory.Matlab( Source, Event, Callback );

Error in curvefit.proplistener (line 25)
listener = makeListener(Factory, Source, PropName, Callback);

Error in curvefit.createListener>iCreateListener (line 39)
    L = curvefit.proplistener(src, eventname, callback);

Error in curvefit.createListener (line 29)
    L = iCreateListener(src, event, callback);

Error in curvefit.ListenerTarget/createListener (line 100)
            L = curvefit.createListener(src, event, callback);

Error in curvefit.gui.FunctionSurface/createAxesLimitListeners (line 285)
                obj.createListener( obj.Parent, 'XLim', @obj.redraw )

Error in curvefit.gui.FunctionSurface (line 104)
            createAxesLimitListeners( obj );

Error in sfit/plot>iPlotSurface (line 96)
hFS = curvefit.gui.FunctionSurface( hParent );

Error in sfit/plot (line 52)
        h1 = iPlotSurface( hParent, obj );

[Geoff Hayes]

Which version of MATLAB are you using? What does it's documentation say about using plot for fit objects?

[Giorgio Menallo]

R2020a

It's the same link you provided, which is also where I got the idea of trying:

H = plot(sf, 'Parent', app.Map )

[Geoff Hayes]

It isn't clear to me why this wouldn't work. Perhaps try creating an example outside of your GUI. You can take any of the examples from fit and then try to plot as

plot(sf, 'Parent', gca )

Does that work or do you see the same errors?

[Giorgio Menallo]

I have tried several variation but the errors are still there.

Here are the main two.

load franke
sf = fit([x, y],z,'poly23')
plot(sf, 'Parent', gca)

It runs but it isn't shown anywhere, unless I create a figure window beforehand.

I have tried to create a simple GUI with nothing other than a button and a UIAxes.

load franke
sf = fit([x, y],z,'poly23')
plot(sf, 'Parent', app.UIAxes)

It retuns the same long list of errors as before.

This is quite puzzling

[Geoff Hayes]

Gorigio - it may be that the UIAxes is not compatible with the fit object (see this older post https://www.mathworks.com/matlabcentral/answers/274880-app-designer-uiaxes-doesn-t-show-results-of-fitting-curve). It suggests that you need to do something similar to

load census;
f=fit(cdate,pop,'poly2');
x = 1700:2000;
y = feval(f,x);
plot(app.UIAxes,x,y)

but I'm not sure if that is valid for your use case.

[Giorgio Menallo]

Geoff, thanks for all the help.

I actually had found the same post and I was already working on a similar solution.

In the end, that's what worked for me:

            X=[wL,wIN1,wIN2,wIN3,wIN1,wIN2,wIN3,wR,wL,wIN1,wIN2,wIN3,wR];
            Y=[hIN,hB,hB,hB,hIN,hIN,hIN,hIN,hBC,hBC,hBC,hBC,hBC];
            Z=[lL,lB1,lB2,lB3,lIN1,lIN2,lIN3,lR,BC1,BC2,BC3,BC4,BC5];
            
            n=(1:length(Z));
            Ztop=(max(Z)+10).*ones(1,length(n));
            plot3(app.Map, X(n),Y(n),Ztop,'.k','markersize',12)
            view(app.Map, 2)
           
            hold(app.Map, 'on')
            
            [x y] = meshgrid([min(X):1:max(X)],[min(Y):1:max(Y)]);
            options = fitoptions('Method','BiharmonicInterpolant');
            sf = fit([X',Y'],Z','biharmonicinterp',options);
            z = sf(x,y);
            surf(x,y,z,'Parent', app.Map,'FaceColor','interp', 'EdgeColor','None')
            axis(app.Map, 'equal')
            caxis(app.Map, 'auto')
            app.Map.YLim = [hB hBC];
            app.Map.XLim = [wL wR];
            view(app.Map, 2)
            colormap(app.Map);
            colorbar(app.Map);
            
            hold(app.Map, 'off')

Answer 3

[Adam Danz]

Starting in MATLAB R2023b, provide the axis handle as the first input to plot the fit line in your app's axes.

plot(ax,___)

plot(app.UIAxes, fitline, a, b)

For a workaround prior to R2023b, see this answer.