Why do I get the error "Unable to set the 'YAxis' property of class UIAxes because it is read-only" when I programmatically assign a new y-axis ruler in MATLAB R2024a?

I have been programmatically changing the type of axis by assigning a new ruler of the correct type. For example, for the y-axis:

a = uiaxes;
a.YAxis = matlab.graphics.axis.decorator.DurationRuler;

I then get the following error:

Unable to set the 'YAxis' property of class UIAxes because it is read-only.

However, I do not receive any error when I do this with the x-axis.

Is this a bug? Why is the behaviour between programmatically assigning a new ruler different for the y-axis and the x-axis? What are the workarounds for this error?

Answer 1

[MathWorks Support Team]

This is not a bug. 

The differing behaviour you experienced between the x and y-axes is due to how they were implemented.

In particular, setting the axes to a different type of ruler was not intended to be a documented workflow. The only officially documented way to change a ruler to a different type is to call a command (such as "yline") that supports duration data. Therefore, a suitable workaround would be:

a = uiaxes;
% Plot a dummy vertical line at a duration value to force the X axis to become a DurationRuler
yline(a, seconds(0)); % This will change the X axis to a duration type
delete(a.Children);    % Remove the dummy line if not needed