Deleting individual plots from a figure

Hi everyone, i'm fairly new to matlab but I will try to explain my question in as much detail as possible. I'm creating a GUI that allows users to create either a line or a circle(specified by coordinates that they put into an inputdlg), and plot it to a graph. This is done with the use of two push buttons (create line, create circle). When each button is pressed, a function runs that creates the shape based on their input. As this can be used various times, I have not assigned the plot in either case to a variable so I cant just use the delete() function. I was wondering, If anyone knew any way of deleting plots from a figure(also based on user input). Im guessing it requires you to either label plots or access the array containing all plots on a figure? Any help would be greatly appreciated and if more information is needed I will provide, thanks, dan. (I've included an example of my create line function so you can see what im doing).

promt = {'Set your X(1) coordinate','Set your Y(1) coordinate', 'Set your X(2) coordinate', 'Set Y(2) coordinate', 'Name your line'}
title = 'Create Line';
lineno = 1;
hold on;
linedraw = inputdlg(promt, title, lineno);                    
x1 = str2num(linedraw{1});
y1 = str2num(linedraw{2});
x2 = str2num(linedraw{3});
y2 = str2num(linedraw{4});
name = linedraw{5};
plot([x1 x2] , [y1 y2], );
hold off;

Answer 1

[Adam]

The plot function returns an argument that is a handle to the plotted object. Use this and just call delete on it. i.e.

hPlot = plot([x1 x2] , [y1 y2], );
...
delete( hPlot );

though try to use a more meaningful name for whatever the specific plot is than hPlot!

[Daniel Morgan]

Thanks for the reply! The only issue is that I can't assign the plots to a single variable, as there is one function for creating lines and it could be used multiple times, so i want the user to be able to delete any plot at any given time?

[Adam]

If you plot multiple lines in a single plot instruction you will get an array of graphics objects handles out as the result - you can delete any single element or multiple elements from this array too.

Or if you make multiple calls to plot you can assign them yourself to an array:

hPlot(1) = plot([x1 x2] , [y1 y2], );
hPlot(2) = plot([x1 x2] , [y1 y2], );
hPlot(3) = plot([x1 x2] , [y1 y2], );

delete( hPlot(2) );

You do need to be careful, depending what you do with those handles afterwards though because you will still have a 3-element vector, you will just have the 2nd element of this being the handle to a deleted object. You can obviously choose to remove this element with

hPlot(2) = [];

if you wish, though obviously this will re-index all subsequent stored plots.

[Daniel Morgan]

Brilliant! Thanls for your help :-)