# Set and enforce axis properties immediately

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slaiyer on 13 Oct 2014
Answered: Robert Cumming on 14 Oct 2014
I have visualization code along the following lines:
subplot(1, 2, 1);
scatter3(N(:,1), N(:,2), N(:,3), '.');
drawnow;
hold on;
for r = 1 : NUM
% ... heavy calculations here
trisurf(Tri(FBtri), XYZ(:,1), XYZ(:,2), XYZ(:,3));
drawnow;
hold on;
end
set(gca, 'XDir', 'reverse');
% End subplot 1
subplot(1, 2, 2);
% Similar code
set(gca, 'XDir', 'reverse');
% End subplot 2
% So on, and so forth...
I need to reverse the X axis, and have found that it only works if I add the property setter after the entire code block for each subplot. This results in the entire subplot being rendered, and then visibly being reversed.
Is there a way that this property can be set and enforced before any contained future objects are computed/rendered, so that everything is shown reversed along the specified axis in the first place?
I would also welcome suggestions towards improving my usage of hold and drawnow, and on how to set and enforce axis reversal (or any axis property in general) for all subplots in the beginning itself with a single call to set, if that's possible.

Geoff Hayes on 14 Oct 2014
You mention subplots, but your above code does not show that. What are you iterating over? Does NUM correspond to each subplot?
Suppose that you have a figure that you wish to add 16 subplots to. Then you could create the figure with the plots, and reverse the x-axis for each plot.
figure; % create the figure
m = 4; % define the number of subplot rows
n = 4; % define the number of subplot columns
hSubplots = zeros(m,n); % create an array for the handles to each subplot
% create/initialize the subplots
for u=1:m
for v=1:m
hSubplots(u,v) = subplot(m,n,(u-1)*n+v);
hold(hSubplots(u,v),'on');
% only reverse the x-axis for the first two rows
if u<=2
set(hSubplots(u,v),'XDir','reverse');
end
end
end
A figure is displayed with sixteen subplots, with the x-axis reversed for all subplots in the first two rows. Now let's plot some data for each subplot
% create/initialize the subplots
[x,y] = meshgrid(1:15,1:15);
tri = delaunay(x,y);
z = peaks(15);
for u=1:m
for v=1:m
trisurf(tri,x,y,z,'Parent',hSubplots(u,v))
axis(hSubplots(u,v),'tight');
end
end
After running the second block of code, we can see that the 8 subplots whose x-axes was reversed still maintains that "reversal" after the trisurf displayed the triangles on that subplot.
You should be able to use the above code as a guide to do the same for your work so that everything is shown reversed along the specified axis in the first place.
##### 2 CommentsShowHide 1 older comment
Geoff Hayes on 14 Oct 2014
Try my example and see if it meets your needs. Run the first block of code and observe that the axes are reversed. Then run the second block of code and see that afterwards, the directions of the subplots have been enforced.
For your case, just see what happens for the first subplot if you do something like
h = subplot(1, 2, 1);
scatter3(N(:,1), N(:,2), N(:,3), '.');
drawnow;
hold(h,'on');
set(h,'XDir','reverse');
for r = 1 : NUM
% ... heavy calculations here
trisurf(Tri(FBtri), XYZ(:,1), XYZ(:,2), XYZ(:,3));
drawnow;
end

Sean de Wolski on 14 Oct 2014
If you don't need the intermediate updates in the loop, pull the drawnow out of the loop and call it once after setting xdir reverse. This way the graphics are only updated after the loop which will save time and it will only show the final result which includes xdir reversed.
slaiyer on 14 Oct 2014
That is a deliberate inclusion. I need to have the objects in every subplot rendered as soon as they are computed.

Robert Cumming on 14 Oct 2014
when you create your subplot set the Xdir then:
subplot ( 1, 2, 1, 'xdir', 'reverse' );
% your other code goes here
subplot(1, 2, 2, 'xdir', 'reverse' );
If this doesn't work it could be due to you use cla - which resets all axes properties, if thats the case then change the default behaviour of the nextplot command (then you dont need hold on).
subplot ( 1, 2, 1, 'xdir', 'reverse', 'nextplot', 'add' );

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