Invalid Handle Object with Subplot

Hi, I would appreciate any help on this matter, thank you for reading :)

I am attempting to do something like the following:

x1 = [1 2 3 4];

y1 = [2 4 6 8];

y2 = [4 8 12 16];

figure; hold on;

h1 = subplot(1,2,1);

hold on;

plot(x1,y1)

h2 = subplot(1,2,2);

hold on;

plot(x1,y2);

set(h1,'title','test1');

set(h2,'title','test2');

However, I get the error:

??? Error using ==> set Value must be a handle

I have also attempted to set both the figure and subplot properties to include 'NextPlot','add' but this did not help.

Thanks for all suggestions!

Answer 1

[Daniel Shub]

The problem is that the property title requires a handle to a text object and not a string. The help http://www.mathworks.com/help/releases/R2011a/techdoc/ref/axes_props.html deals with this. You can create a text object in the appropriate axis with:

axes(h1);
set(h1,'title',text('string', 'test1'));
axes(h2);
set(h2,'title',text('string', 'test2'));

You might just want to use:

title(h1, 'test1');

[Erin MacMillan]

Hi Daniel,

Thanks, I think this is getting closer to the root of the problem. I tried the syntax:

set(h1,'title',text('string', 'test1'));

but now I got another error:

??? Error using ==> set

Error using ==> set

Title must be an existing text child of axes

Do you know what that means?

Thanks again!

[Daniel Shub]

That is because you left out the axes(h1) part. The text command puts the text into the current axes (in this case h2) and you want it in h1.

[Erin MacMillan]

Yes that was it! Thank you very much!!

Answer 2

[the cyclist]

Are you just trying to set titles of each subplot?

x1 = [1 2 3 4];

y1 = [2 4 6 8];

y2 = [4 8 12 16];

figure; hold on;

h1 = subplot(1,2,1);
title('test1')

hold on;

plot(x1,y1)

h2 = subplot(1,2,2);
title('test2')
hold on;

plot(x1,y2);

Part of the problem of the way you were trying to do it was that h1 and h2 are the handles for the lines plotted, not for the plotting axes.

[Erin MacMillan]

Hi,

I am actually trying to do something a lot more complicated, but I boiled the problem down to that example. I need to set some properties of a subplot axes when the plots are run in a loop, so the handles get overwritten. I think you have stated the root of the problem: "h1 and h2 are the handles for the lines plotted, not for the plotting axes". How do I make a handle for the plotting axes in a subplot?

Thanks!

[Daniel Shub]

The handles h1 and h2 are handles to the axes since they are returned by subplot. The problem is that the title property does not want a string, but rather a handle.