How to plot arrow with data coordinates in Matlab?

Question

I know there is a function named annotation can plot arrows or double arrows. But annotation can only plot in normalized unit. For example:

annotation(\'arro         


        

Answer 1

After creating the annotation object you should set the property Units to an absolute one. Example:

arrowObj = annotation('arrow', [0.1 0.1], [0.5 0.5]);
set(arrowObj, 'Units', 'centimeters');
set(arrowObj, 'Position', [1 1 3 5]);

Answer 2

If I remember correctly you need to calculate the position of the axes in relation to the figure.

it should go like:

%% example plot
clf
plot(rand(5,2)*5)
%% get info specific to the axes you plan to plot into
set(gcf,'Units','normalized')
set(gca,'Units','normalized')
ax = axis;
ap = get(gca,'Position')
%% annotation from 1,2 to 3,4
xo = [1,3];
yo = [2,4];
xp = (xo-ax(1))/(ax(2)-ax(1))*ap(3)+ap(1);
yp = (yo-ax(3))/(ax(4)-ax(3))*ap(4)+ap(2);
ah=annotation('arrow',xp,yp,'Color','r');

Note Fixed offset in original calculation - ap(3),ap(4) are width and height of gca, not corner positions