How to detect if a figure exist?

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John on 14 Jan 2016
Commented: Stephen23 on 13 Nov 2022
To save the figure if one exists with:
the problem is that if no figure exists, it'll create a figure. How to detect if a figure exist before using above saveas command to avoid the creation of an empty figure?

Accepted Answer

Brendan Hamm
Brendan Hamm on 14 Jan 2016
In 2014b and later you can query whether the Graphics Root objects has any children:
g = groot;
isempty(g.Children) % True if there are no open graphics objects, false otherwise
John on 14 Jan 2016
Thanks, I did this and it worked as well:
fig = get(groot,'CurrentFigure');
if ~isempty(fig)
Roger Breton
Roger Breton on 8 Feb 2022
Thank you for sharing this tidbit of code!
It worked perfect for me in my script.
But I could not find "CurrentFigure' in the list of properties when I issued get(fig) from the command window in debuig mode?

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More Answers (1)

Stephen23 on 14 Jan 2016
Edited: Stephen23 on 14 Jan 2016
The most reliable solution is to move your programming up a notch: use explicit handles and keep track of them.
While gcf and gca are fine for the command-line and playing with scripts, when you want to write more advanced functions then:
  • do not use gcf, gca.
  • store the handle of every axes, figure, and other relevant objects.
  • explicitly specify the parent of every object when it is created, plotted, etc.
When you code properly then your quest is trivial using ishghandle:
Stanislav Ginzburg
Stanislav Ginzburg on 13 Nov 2022
Sometimes you may get handle on empty object plot([1,2], [NaN, NaN]); Result of ishghandle is true, Groot return handler of figure. And not empty too. The good practice is to prevent save empty objects.
Stephen23 on 13 Nov 2022
"The good practice is to prevent save empty objects."
No, empty plots may also be information: it may be a perfectly valid and important result that for some figure nothing is plotted. This depends entirely on the specific situation and thus is the responsibility of the user to check.

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