text with arrow pointer

i need help with

how to draw an arrow to point in a specific direction

Answer 1

[Cris LaPierre]

See here: https://www.mathworks.com/help/matlab/ref/annotation.html

[Tasneem Abed]

how to specify

x and y??

[Cris LaPierre]

By default, these are in normalized units (percentage of your x and y range).

https://www.mathworks.com/help/matlab/ref/annotation.html#br2_upx-1-x

https://www.mathworks.com/help/matlab/ref/annotation.html#br2_upx-1-y

There is an example on the linked page that demonstrates how to use it. The first value in x and y correspond to the tail position, and the 2nd values correspond to the head.

[Tasneem Abed]

the x-axis is from 0 to 24 how to convert that to 1

and so is the y-axis???????

[Walter Roberson]

Be careful, the positions for annotation() can only be absolute coordinates or coordinates normalized to the figure. There is no way to specify data units.

There are File Exchange contributions to make it easier to use data units

[Cris LaPierre]

Here's an example of one such program on the File Exchange

• https://www.mathworks.com/matlabcentral/fileexchange/10656-data-space-to-figure-units-conversion

% add an annotation pointing to the 5th data point
x = 0:24;
y = randi(6000,size(x));
plot(x,y)
S = sprintf("A2="+y(5));
xa = [-1 0]+x(5);
ya = [-1000 0]+y(5);
[xaf,yaf] = ds2nfu(xa,ya);
annotation('textarrow', xaf, yaf,'String',S)