How to automatically get the axis of a figure in Live Editor?

I'm working with images on a live script and it would be much faster for me if it was possible to get the figure axis. However I don't even manage to get the figure handles so I don't know if a solution exists?

Thank you

[Riccardo Scorretti]

Normally, if you create new figures by:

hndl = figure();

you should get the handle to the figure. Can you provide a simple example of what you need to do?

[Grelier Matthieu]

Thanks but this does not work inside the Live Editor it seems. I just display an image with imagesc and then I want to zoom on one of the feature and basically extract the associated axis limits. It's easily achieved outside the Live Editor but it seems the figures react differently in live scripts.

Answer 1

[Cris LaPierre]

You can get the axes object in a figure the same way you would outside of a live script.

Option 1: capture the axes object by creating it with code. Be sure to specify the target axes when plotting, or the plot command will create a new figure and axes.

ax = axes;
plot(ax,x,y)

Option 2: plot your data as you normally would. Once created, capture the current axes using the gca command.

plot(x,y)
ax = gca;

This works for most plot types, but some plots may behave differently. If neither approach works for you, please share your code.

[Grelier Matthieu]

Thank for the ideas but both options do not seem to work in the Live Editor. Here's the code I'm using.

ax = axes;
imagesc(ax,test_image);colorbar;colormap(jet)

This gives the following image where we have a strange superposition of the axis:

After that, I zoom on one of the feature of the image basically:

And here I want to read the axis limit. I tried with:

get(ax,'Xlim')

But it gives the limits of the full image. For information, the code works outside the Live Editor.

[Cris LaPierre]

I see. Where are you calling the get function? In the live editor or in the command window?

I think what is happening here is that the image you see in the livescript is a snapshot of the figure at a specific time, and not the actual figure. So while you can zoom in and otherwise interact with the snapshot, it is not the axes captured in ax.

I'm afraid I don't know a way to do exactly what you want using the image embedded in a live script. Ideas that immediately come to mind are to either

1. use the Update Code option to add code to your script to update the actual figure axes to those you established via manually zooming. This appears automatically

2. pop the figure out of the live script so that it behaves as you are expecting. You can do that programmatically with the following code. Now when you interact with the figure window that opens, you are modifying the axes captured in ax.

figure('Visible','on')

[Grelier Matthieu]

I was calling the get function in the live editor. I see. I think your first idea is the best compromise so I'll go for it. Thank you.

Answer 2

[Steven Lord]

If you call the function that displays the image with an output argument, you can determine which figure contains that graphics object using the ancestor function.

h = plot(1:10);
f = ancestor(h, 'figure')

f = 
  Figure (1) with properties:

      Number: 1
        Name: ''
       Color: [1 1 1]
    Position: [671 661 577 433]
       Units: 'pixels'

  Show all properties

f.Color = 'r';

The ancestor function lets you ask for other ancestors as well:

ax = ancestor(h, 'axes')

ax = 
  Axes with properties:

             XLim: [1 10]
             YLim: [1 10]
           XScale: 'linear'
           YScale: 'linear'
    GridLineStyle: '-'
         Position: [0.1300 0.1100 0.7750 0.8150]
            Units: 'normalized'

  Show all properties

isequal(f, ancestor(ax, 'figure')) % true

ans = logical
   1

[Grelier Matthieu]

Thanks for the answer. Same problem as before though, it works outside the Live Editor but not in it. It seems it cannot be done in lives scripts...