Data space to figure units conversion

A utility function to simplify use of annotation function

Description

The annotation function, which allows you to programmatically add a wide range of annotations to your figure, requires coordinates to be specified in normalized figure units. I have found that I almost always want to specify my annotations in data space (i.e., based on the values of data displayed in an axes).

This utility function converts coordinates in data space into normalized figure coordinates, for input to annotation. Some annotations require you to specify (x,y) pairs, while others require a 4 element position vector. This function supports both syntaxes.

Here's a simple example:
% Create some data
t = 0:.1:4*pi;
s = sin(t);
 
% Add an annotation requiring (x,y) coordinate vectors
plot(t,s);ylim([-1.2 1.2])
xa = [1.6 2]*pi; % X-Coordinates in data space
ya = [0 0]; % Y-Coordinates in data space
[xaf,yaf] = ds2nfu(xa,ya); % Convert to normalized figure units
annotation('arrow',xaf,yaf) % Add annotation

Note: I believe annotation was introduced in MATLAB 7.

• Acknowledgements: This submission has inspired the following:; axescoord2figurecoord
• MATLAB release: MATLAB 7.2 (R2006a)

[kerr hatrick.]

very useful util. for purposes of automatic plot annotation. thx++ mr Hirsch.

[Axiom .]

Works as advertised. A necessity if you prefer to do your annotations in code rather than editing the plot. Thanks!

[Vivek Goyal]

Easy to use, and seems to work correctly. As soon as I learned of the annotation function, I realized that I needed this coordinate conversion function. Thanks.

[Lucian P]

Doesn't work in R12a

[Scott Hirsch]

Lucian -

Sorry about that! I was using a syntax introduced in R13. Easy enough fix - change '&&' to '&' in line 58 (2 times). I tested in R12, and it works with this fix. This should work for slightly older versions, too. Note that the examples won't work, though, since ANNOTATION was introduced sometime after R12.

[Benoît Valley]

This a nice and useful code, but it do not work if DataAspectRatioMode or PlotBoxAspectRatioMode are set to 'manual'. So it would be even nicer if this code would be improved to managed such case.

[Tim Mullen]

 

[Scott McClure]

This function does not deal with log axes.

[Till Junge]

Your function doesn't work with equal axes. example:
function bla()
close all
a=pi/4;
r=0:1e-2:1;
f=@(r) 1/2*a*log(1+(tan(a*r)).^2);
createfigure(r,f(r),f)

function createfigure(X1, Y1,f)
%CREATEFIGURE(X1,Y1)
% X1: vector of x data
% Y1: vector of y data

% Auto-generated by MATLAB on 17-Mar-2008 14:49:27

% Create figure
figure1 = figure('XVisual',...
    '0x22 (TrueColor, depth 24, RGB mask 0xff0000 0xff00 0x00ff)');

% Create axes
axis1=axes('Parent',figure1);
box('on');
grid('on');
hold('all');
axis equal
ylim([0,.3])
xlim([0,1])

% Create plot
plot(X1,Y1);
r=.7
the=r*pi/4
[vpx,vpy]= ds2nfu(gca,[r r],[0,f(r)]);
annotation(gcf,'arrow',vpx,vpy);
[nx,ny] = ds2nfu(gca,[r r-.2*sin(the)],[f(r) f(r)+.2*cos(the)]);
annotation(gcf,'arrow',nx,ny);

[Matt Brunner]

Works fine for me. Thanks for sharing.

[Yan Luo]

working for me. great

[Maxie]

Very useful!
Can add text at the tail of the arrow using 'textarrow' ?
Thanks!