MATLAB: How to orient a text arrow

text to plots

Hello,

I am making a figure and added the x, y, z axes with labels for positve/negative x, y, and z using text(x,y,z,'leftarrow'). It looks good for the z-axis, but needs to be rotated for the xa and y axes. Is there a way to make an arrow that goes up and to the left (i.e. does something like 'leftuparrow' exist)?

Best Answer

Hello,

You can specify the start and end of the arrow, as well as the type of arrow using an annotation.

It'll look something like:

x = [.2 .6];
y = [.1 .5];
annotation('textarrow',x,y)

which draws a text arrow from the point (.2*x axis range, .1*y axis range) to (.6*x axis range, .5*y axis range).

Hope this helps!

Related Solutions

MATLAB: Label 3D axes on multiple sides

Unfortunately you can only label one side of each axis using the xlabel, ylabel, zlabel functions.

A common workaround in Matlab is to add a second invisible axis that hosts the second set of axis labeles on the other side of the axes but XAxisLocation and YAxisLocation which determine the side of the axis and label are only supported in 2D axes and there is no ZAxisLocation. Double bummer.

If this is for publication or will be inserted into a document, I recommend labeling the axes outside of Matlab (powerpoint, for example).

A workaround in Matlab for 3D axes is to use annotation or text to add what appears to be an axis label but behaves slightly differently. Text objects are anchored to data units and annotation objects are anchored to normalized figure units. So if you use text() you must do so after setting the final axis limits, rotation, and view and if you pan the data, the pseudo-axis-labels will move along with it. If you use annotation() and the axis size adjust or rotates, the label will not follow. Of course you could set up a listener to fix that.

Here's a simple example using text().

This pseudo axis labels are highly customized to the current viewing angle and it will not look as nice if the axis is rotated!

fig = figure();
ax = axes(fig); 
[X,Y,Z] = peaks(25);
surf(ax, X,Y,Z)
box on
xlabel(ax, 'Real x label')
ylabel(ax, 'Real y label')
zlabel(ax, 'Real z label')
xlim(ax, [-3 3])
ylim(ax, [-3 3])
zlim(ax, [-8 8])
xlmax = max(xlim(ax))+range(xlim(ax))*.05; 
ylmax = max(ylim(ax))+range(ylim(ax))*.05; 
ylmin = min(ylim(ax))-range(ylim(ax))*.05; 
zlmax = max(zlim(ax))+range(zlim(ax))*.05; 
x2lab = text(mean(xlim(ax)), ylmax, zlmax, 'Pseudo-x-label','Rotation',15,'HorizontalAlignment','center');
y2lab = text(xlmax, mean(ylim(ax)), zlmax, 'Pseudo-y-label','Rotation',-25,'HorizontalAlignment','center');
z2lab = text(xlmax, ylmin, mean(zlim(ax)), 'Pseudo-z-label','Rotation',-90,'HorizontalAlignment','center');
set([x2lab, y2lab, z2lab],'FontName', ax.FontName, 'FontSize', ax.FontSize);

MATLAB: Pointer on the graph.

Sumit had a good suggestion if you want to use colors and marker shapes. If you want pointers like arrows, then you can use the annotation() function:

annotation
Create annotation objects 
Syntax
annotation(annotation_type)
annotation('line',x,y)
annotation('arrow',x,y)
annotation('doublearrow',x,y)
annotation('textarrow',x,y)
annotation('textbox',[x y w h])
annotation('ellipse',[x y w h])
annotation('rectangle',[x y w h])
annotation(figure_handle,...)
annotation(...,'PropertyName',PropertyValue,...)

Of course you'd need the x,y coordinates of the arrow endpoints first.

Best Answer

Related Solutions

MATLAB: Label 3D axes on multiple sides

MATLAB: Pointer on the graph.

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