App Designer UIAxes doesn't show results of fitting curve

Hi, I have generated an app in Guide which uses three different axis to show three different fit models for the same dataset (x,y). I ma trying now to recreate the same code with App design. The functions I am using are the same and the dataset is imported from Excel files. the problem I am facing is that in App Designer I can't plot x, y and the fit results as I do in GUIDE. Not sure if I am doing something wrong or simply is not possible. The code is as follows:

app.x = data(:,1);
app.x(isnan(app.x))=[];
app.y  = data(:,2);
app.y(isnan(app.y))= [];
ylog = log((min(app.y)-app.y)+0.01);
mdl = polyfit(app.x,ylog,1);
b = mdl(:,1);
a = -min(app.y);
c = max(app.y);
ft =fittype('a*exp(-b*x)+c', 'independent', 'x', 'dependent', 'y');
opts =fitoptions ('Method', 'NonlinearLeastSquare');
opts.display = 'Off';
opts.StartPoint = [a b c];
opts.MaxFunEvals = 1200;
opts.MaxIter = 800;
[res, gof ] = fit( app.x, app.y, ft, opts);

plot(app.UIAxes,  app.x, app.y, 'ro')

eq = ['y= ',num2str(res.a), '*exp(-' num2str(res.b) '*RR)+ ' num2str(res.c)];
app.Label3.Text = eq;
app.Label4.Text = ['a = ',num2str(res.a)];
app.Label5.Text = ['b =- ',num2str(res.b)];
app.Label6.Text = ['Rsquare = ',num2str(gof.rsquare)];

if I try to plot res, the error I get is : Non-numeric data is not supported in 'UIAxes'

Any help would be much appreciated

Best Regards Marcello

Answer 1

[Mike Garrity]

UIAxes has a number of limitations in this first release. From the error message, I would guess that either app.x or app.y is a datetime or duration. In R2016a, plotting into UIAxes doesn't support those, and you'll have to convert them to numerics with something like datenum.

[Marcello]

hi Mike, thanks for the answer. app.x and app.y are numeric values and I can plot them without problems. what is not working is the result of fitting of app.x and app.y. in GUIDE I use:

plot(res, x,y)

and it works perfectly, but in App designer if I write

plot(a.UIAxes, res, app.x, app.y)

I get the error as per the above question Marcello

[Mike Garrity]

Sorry, what's res?

[Marcello]

Hi Mike res is the results of fitness

[Mike Garrity]

Oh, got it. You're getting the plot method on the fit class, not the regular plot function. No UIAxes doesn't work with that. You'd need to have the fit class generate a list of points and then plot that:

load census;
f=fit(cdate,pop,'poly2');

x = 1700:2000;
y = feval(f,x);
plot(uiaxes,x,y)

[Marcello]

Thank you, that was helpful. I think I will keep on working with GUIDE for this project.