How to get the values of the XAxis Minor Ticks (of an inset plot)

Question

Sim 2024-9-2

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2149579-how-to-get-the-values-of-the-xaxis-minor-ticks-of-an-inset-plot

编辑： Sim 2024-9-3

I have an inset plot, in a log-scale, and I would like to get the values of its XAxis Minor Ticks, with the following command:

ax2.XAxis.MinorTickValues

However, when I run the following code

% create a plot

x1 = linspace(0,1000);

y1 = sin(2*pi*x1);

plot(x1,y1)

set(gca,'Fontsize',20,'FontWeight','normal','LineWidth',1);

% create the inset plot

ax2 = axes('Position',[.45 .45 .4 .4]);

box on

plot(x1,y1) % <-- inset plot

set(ax2,'XScale','log') % <-- set log-scale for the x-axis of the inset plot

set(ax2,'Fontsize',20,'FontWeight','normal','LineWidth',1);

% Result

ax2.XAxis.MinorTickValues

ans = []

In other words, the followin command

ax2.XAxis.MinorTickValues

returns an empty array!

Another comment: if I go to the Command Window (when the figure is still on the monitor of the computer) and I type the same command, I get the correct values

>> ax2.XAxis.MinorTickValues
ans =
  Columns 1 through 9
          10          20          30          40          50          60          70          80          90
  Columns 10 through 18
         100         200         300         400         500         600         700         800         900
  Column 19
        1000
        
        

How can I get the values of the XAxis Minor Ticks of an inset plot, within a code, and not as an "external command", in the Command Window?

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Answer 1

Gayathri 2024-9-2

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编辑：Gayathri 2024-9-2

在 MATLAB Online 中打开

Hello @Sim,

I understand that you are getting an empty array while running "ax2.XAxis.MinorTickValues" in code but getting output while running the same code in command window. It might be due to the timing of when the "MinorTickValues" property is being accessed. In MATLAB, certain properties, like "MinorTickValues", may not be initialized until the plot is fully rendered and visible. You can use "drawnow" to force MATLAB to complete the rendering of the figure before accessing the "MinorTickValues" property as shown below.

drawnow;
ax2.XAxis.MinorTickValues

For more information about "drawnow" you can refer the below mentioned link.

https://www.mathworks.com/help/matlab/ref/drawnow.html

Hope this resolves the issue mentioned.

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Sim 2024-9-2

Thanks a lot @Gayathri :-)

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Answer 2

Star Strider 2024-9-2

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2149579-how-to-get-the-values-of-the-xaxis-minor-ticks-of-an-inset-plot#answer_1509199

编辑：Star Strider 2024-9-2

在 MATLAB Online 中打开

Assign the output to a variable —

% create a plot

x1 = linspace(0,1000);

y1 = sin(2*pi*x1);

plot(x1,y1)

set(gca,'Fontsize',20,'FontWeight','normal','LineWidth',1);

% create the inset plot

ax2 = axes('Position',[.45 .45 .4 .4]);

box on

plot(x1,y1) % <-- inset plot

set(ax2,'XScale','log') % <-- set log-scale for the x-axis of the inset plot

set(ax2,'Fontsize',20,'FontWeight','normal','LineWidth',1);

% Result

ax2.XAxis.MinorTick = true

ax2 =

Axes with properties: XLim: [10 1000] YLim: [-1 1] XScale: 'log' YScale: 'linear' GridLineStyle: '-' Position: [0.4500 0.4500 0.4000 0.4000] Units: 'normalized' Use GET to show all properties

ax2_mtv = ax2.XAxis.MinorTickValues

ax2_mtv = 1x19

10 20 30 40 50 60 70 80 90 100 200 300 400 500 600 700 800 900 1000

<mw-icon class=""></mw-icon>

For some reason, this is being inconsistent here. It appears to be necessary first to turn the minor ticks on, and second not to suppress (with at trailing semicolon ‘;’) the command that turns them on. I get the same behaviour in MATLAB Online. This behaviour may be a bug.

EDIT — Corrected typographical errors.

.

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Star Strider 2024-9-2

在 MATLAB Online 中打开

My pleasure!

I have no idea what the problem is. The solutiion I posted worked for me here and in MATLAB Online.

It works if I re-position the call to it —

% create a plot

x1 = linspace(0,1000);

y1 = sin(2*pi*x1);

plot(x1,y1)

set(gca,'Fontsize',20,'FontWeight','normal','LineWidth',1);

% create the inset plot

ax2 = axes('Position',[.45 .45 .4 .4]);

box on

plot(x1,y1) % <-- inset plot

set(ax2,'XScale','log') % <-- set log-scale for the x-axis of the inset plot

set(ax2,'Fontsize',20,'FontWeight','normal','LineWidth',1);

ax2.XAxis.MinorTick = true

ax2 =

Axes with properties: XLim: [10 1000] YLim: [-1 1] XScale: 'log' YScale: 'linear' GridLineStyle: '-' Position: [0.4500 0.4500 0.4000 0.4000] Units: 'normalized' Use GET to show all properties

ax2_mtv = ax2.XAxis.MinorTickValues

ax2_mtv = 1x19

10 20 30 40 50 60 70 80 90 100 200 300 400 500 600 700 800 900 1000

<mw-icon class=""></mw-icon>

% Set the axes limits

xlim([0 60])

ylim([0 Inf])

% Result

% % ax2.XAxis.MinorTick = true

% ax2_mtv = ax2.XAxis.MinorTickValues

This behaviour is just strange!

.

dpb 2024-9-2

"... and I do not understand the reasons behind this behaviour..."

Buried in the innards of HG2; it attempts to minimize the number of screen refreshes to keep graphics response time as quick as possible.

I would hypothesize that the requested action of simply returning the values doesn't trigger a screen refresh because nothing has happened that will cause the graphics display to change so there is no need for a refresh at that point programmatically. Changing the focus to the command window, otoh, causes a refresh and then the internal data have been updated.

I tried the same thing as @Star Strider and got it to work the first time, but then it didn't later; only Mathworks would have the ability to actually explain explicitly why...

Sim 2024-9-3

Thanks @dpb :-)

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Answer 3

dpb 2024-9-2

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2149579-how-to-get-the-values-of-the-xaxis-minor-ticks-of-an-inset-plot#answer_1509214

编辑：dpb 2024-9-2

在 MATLAB Online 中打开

@Gayathri recognized the underlying problem which can be very confusing because it is so erratic in what does/does not get updated there's no predicting what operation(s) require it -- and it's rare enough it is almost never on one's radar unless one just happens to "get bit" a second time recently enough after having had a first occurrence.

However, for complicated handling of such graphics, I would strongly recommend keeping a better track of object handles; my first thought was that since the code wasn't encapsulated in a function the axes handles were getting mixed up and you were accessing another axis in the command window, but that alone didn't always solve the problem; it worked once and like @Star Strider's thoughts, thought had it solved, but then a second run after adding only some additional comments, not code, it failed again and couldn't get it to work correctly even reverting back. It's truly a mind-boggling symptom when it does occur.

Anyways, I'd suggest something more on the order of

% create a plot

x1 = linspace(0,1000);

y1 = sin(2*pi*x1);

hF=figure; % create a figure handle to put stuff into...

hAx1=axes(hF,'Fontsize',20,'FontWeight','normal','LineWidth',1); % put the axes in the desired figure

hL1=plot(hAx1,x1,y1); % and the first line in that axis

% create the inset plot

hAx2=axes(hF,'Position',[.45 .45 .4 .4],'Fontsize',20,'FontWeight','normal','LineWidth',1, ...

'box', 'on');

hL2=plot(hAx2,x1,y1); % <-- inset plot

hAx2.XScale='log';

drawnow

hAx2.XAxis.MinorTickValues

ans = 1x19

10 20 30 40 50 60 70 80 90 100 200 300 400 500 600 700 800 900 1000

<mw-icon class=""></mw-icon>

Now you have access to everything specifically and are sure are talking to the right object and focus is where intend it to be...

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dpb 2024-9-3

Well, that depends... :) I agree @Gayathri was the first to identify the issue w/ the event queue not being updated and that drawnow solves the initial issue, so precedence goes there. Personally, whether or not I was the one to point it out and provide the other code, in cases of mixing multiple axes I think good practice is to always identify the actual objects...

Sim 2024-9-3

编辑：Sim 2024-9-3

Yes, sorry, I need to give credit to @Gayathri for identifying the issue first. I am using your sligtly more sophisticated solution, even though the initial hint comes from @Gayathri........ I would really like to accept all the answers... I could, mabye, accept the @Gayathri answer, and ask if people could upvote your answer in order to reach 4 points each, or, viceversa... You all deserve credit!

Also the @Star Strider solution is cool :-)

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How to get the values of the XAxis Minor Ticks (of an inset plot)

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