update objects' coordinate of the same plot !!!!!!!!!!!!!!!!!!!

Hallo,

I am trying to plot the changing coordinate of two objects and i wasn't successful yet. So, i was wondering if someone can give me a help. To make it clear the situation look like this:

assume following two objects

classdef user1 

properties(SetObservable=ture)
coordinate
end
end

classdef user2 

properties(SetObservable=ture)
coordinate
end
end

classdef updateGraph

methods

function obj = updateGraph(array_obj)
               addlistener(array_obj,'coordinate','PreSet',@(x,y)update(obj,src,evnt))
end

function update(obj,src,evnt)
plot(src.coordinate);
end
end
end

It doesn't work since for each call of update a new plot is been generated. How can I do to just update coordinate on the same graph?

Thanks

Bolivar

[Bolivar]

pretty good, Thanks!

[Sven]

No problem Bolivar, remember to hit "accept" if the question is answered.

Answer 1

[Sven]

Hi Bolivar,

Let's just go with one object first for simplicity:

Here's the contents of the user1 class:

classdef user1 < handle
    properties(SetObservable=true)
        coordinate
    end
    properties
        coordinatePlotHandle
    end
    methods (Static = true)
        function update(src,evnt)
            obj = evnt.AffectedObject;
            if isempty(obj.coordinatePlotHandle)
                obj.coordinatePlotHandle = plot(obj.coordinate(:,1),obj.coordinate(:,2));
            else
                set(obj.coordinatePlotHandle, 'XData', obj.coordinate(:,1), 'YData', obj.coordinate(:,2))
            end
        end
    end
end

Now you can make a user1 object:

U = user1

Now you can tell it what should happen after its coordinate is updated:

addlistener(U,'coordinate','PostSet',@user1.update);

Now you can update its coordinate(s).

U.coordinate = [1 1; 2 4]
U.coordinate = rand(5,2)

You'll notice that the first time its coordinate was set, the event was triggered and a plot was made, with the plot handle being retained and stored in U.coordinatePlotHandle. The next time the coordinate is set, that plot handle is simply updated.

Does that help answer your question?