Setting labels and titles of axes extremely slow

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JM
JM 2017-12-14
评论： Justin 2021-2-13
In my use case the setting of labels and the title of axes takes up to a second or more each and I would like to know why and how I can avoid this.
My use case is as follows: I have programmatically created a 1300x800 figure using:
mainfig = figure(...
'Units','Pixels',...
'Position',[50 70 1300 80],...
'Name','abc',...
'DockControls','off',...
'Resize','off',...
'NumberTitle','off');
and added about 6~8 custom sized axes to it using:
axes(...
'Parent',mainfig,
'Units','pixels',
'Position',ex [1 2 3 4]);
Creating this window, these axes and the plots that use these axes using:
plot(ax,...)
is fine and takes up next to no time in the profiler.
However when I add labels and a title to the axes I am seeing up to 1.5 seconds of runtime for each item set. Here is an example from the MATLAB R2015a profiler (problem occurs in R2015a, R2016b, R2017b):
Line Code Calls Total Time %Time
48 ax.XLabel.String = 'blablabla... 1 1.412 s 33.3%
50 ax.Title.String = 'blablabla... 1 1.379 s 32.5%
49 ax.YLabel.String = 'blablabla... 1 1.375 s 32.4%
...
The profiler shows these as 100% self time and does not show the innards of these lines.
Also, in this case using xlabel() or ax.XLabel.String makes no difference in time cost.
So, to repeat, I would like to know why and how I can avoid this. It should not be normal that putting a single piece of text somewhere in a GUI costs an eternity of CPU time.
A test case is provided here: https://pastebin.com/wBjxydju
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Massimo Ciacci
Massimo Ciacci 2018-7-22
编辑：Stephen23 2018-7-22
For me the delay depends on the data size. I guess profiler assigns the time to the lines following plot instead on to the plot itself...
Version: '4.6.0 NVIDIA 391.35'
Vendor: 'NVIDIA Corporation'
Renderer: 'GeForce GTX 1070/PCIe/SSE2'
MaxTextureSize: 32768
Visual: 'Visual 0x09, (RGBA 32 bits (8 8 8 8), Z depth 24 bits, Hardware acceleration, Doub...'
Software: 'false'
SupportsGraphicsSmoothing: 1
SupportsDepthPeelTransparency: 1
SupportsAlignVertexCenters: 1
Extensions: {375x1 cell}
MaxFrameBufferSize: 32768
Massimo Ciacci
Massimo Ciacci 2019-9-24
I confirm that quering properties of axis is slower when there is a lot of stuff plotted on them. A good workaround which I found myself again to use today is to fix all axis properties BEFORE plotting anything on them.

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回答（1 个）

Massimo Ciacci
Massimo Ciacci 2019-10-8
I think I found a nice workaround
% (1) set all curves invsibile, for a good speed up for label handles retrieval
axChild = get(gca,'Children');
allCurves = findobj(axChild,'type','line');
set(allCurves,'visible','off');
% (2) fix/change labels
% (3) restore visible
set(allCurves,'visible','on');
as an example you can try the following plot code which plots 20M points on two curves
close all
clearvars
tic
profile off
profile on
SPEED_UP = 1;
NN = 20e6;
figure(100); grid on; hold on; axh=gca;
plot(1:NN,1:NN);
plot(1:NN,-(1:NN));
if SPEED_UP
axChild = get(gca,'Children');
allCurves = findobj(axChild,'type','line');
set(allCurves,'visible','off');
end
xlabel('x'); ylabel('y');
set(axh,'xscale','log');
xlh = get(axh,'xlabel');
if SPEED_UP
%Restore visibility
set(allCurves,'visible','on');
end
profile viewer
toc
Elapsed time is 2.147400 seconds. SPEED_UP = 0
Elapsed time is 0.690461 seconds. SPEED_UP = 1
profiler_before_after_NEW.png
  2 个评论
Massimo Ciacci
Massimo Ciacci 2019-10-8
I also noticed that this trick can help speed up linkaxes in the same way, by setting allCurves to invisible in both axes before linking ...
Justin
Justin 2021-2-13
Strangely neither workaround (setting labels before plotting nor hiding graph objects when setting labels) seems to work when you are plotting histograms rather than lines. At least in 2020b anyway.

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