How not to delete one element of a figure when using cla?

I have a map with coastlines and sampling stations that are added from other scripts using the command plot. When I move on to the next data set, I need to initialize the plot. What I want specifically is to keep the coastline plots (handle 'h' as below), but clear everything else (e.g., the sampling stations plotted on the map).

cla(app.mapPlot2);                
                  
h = patch(app.mapPlot2, M2(:,1), M2(:,2), [0.62,0.83,0.50]);

My current program as above would delete everything including coastalines. Is there a way I can delete everything but the 'h' handle?

Many thanks!

Answer 1

[Walter Roberson]

No. cla always deletes the children of the axes.

You could put a copy of the object to keep into an axes in an invisible figure and copyobj() it instead of recreating it. However you mentioned mapping toolbox and one thing that cla does is reset back to a regular axes instead of a mapping axes and trying to copyobj a mapping child into a regular axes could easily be a problem. Like it would be easier to copyobj the entire axes.

[Leon]

Very cool. Many thanks!

One of the reasons I want to keep the coastline is because it is quite a laborous process with a loop to plot them:

for i=1:200;
    M2 = [];
    for j=1:m;
       if M(j,3)==i;
           M2=[M2;M(j,1:2)];
       end
    end
    patch(app.mapPlot2, M2(:,1), M2(:,2), [0.62,0.83,0.50]);
end;

In this case, how can I save the loop items into one graphic object?

BTW, is it possible to save the copyobj value into a *.mat file?

[Walter Roberson]

After the above, you can save app.mapPlot2 into a variable and save() the variable, and you can load() again.

But what I would suggest in your case is creating a second axes that is over top of the first axes, with 'background', 'none' so it is transparent, and do all your temporary drawing in it. You can cla() it without affecting the axes you drew the coastline into.

[Leon]

Thank you so much!

I have no idea how to let the 2nd axes to be on top of the first axes.

Is my current axes app.mapPlot2? If I create another one called app.mapPlot2b.

How do I overlay them?

[Walter Roberson]

If you set the Position of the second axes to be the same as the Position of the first axes, then the second one will be on top of the first provided it was drawn later. You can use uistack() to force a particular relative position to be certain.

[Leon]

Got you. Thanks!

Answer 2

[Stijn Haenen]

Maybe you can delete one of the 'Children' of the figure.

type:

h.Children

and check if there is any data that can be deleted.

or

h.Children.Children

[Leon]

Thanks for pointing me to that direction.

To clarify, I do not want to delete anything about the h handle. I just want to delete the sampling station plots from other scripts with unknown handles.

Thanks.