How to draw an arrow in Matlab?

Question

I'm trying to draw an arrow in matlab graph, without any success.

Code example:

function [ output_args ] = example( input_args )

figure ('Name', 'example');
x = [10 30]
y = [10 30]
xlim([1, 100])
ylim([1, 100])
arrow (x, y) ???
end

Is there any function in matlab that can draw arrow ? Thanks

Timmerman

when using "annotation('arrow',x,y)" Im getting error... ? – Timmerman

how are you using it? what do you enter? anyway there are 2 answers below already... – Pycnometer

In the case of publication quality graphics, my solution is sadly to give up fighting with Matlab, export to EPS, and use Adobe Illustrator when I need things like arrows and precise text. It sucks, but I'm a lot happier, and the resulting figures look much better. – Anodize

Answer 1

You can use the (well-documented) DaVinci Draw toolbox (full disclosure: I wrote/sell the toolbox, though arrows are free). Example syntax and example output are below. [UPDATE: The website that distributed this code is now closed. See note in comments.]

davinci( 'arrow', 'X', [0 10], 'Y', [0 2], <plus-lots-of-options> )

Ribbonwood

The link is broken. – Goldshell

Sorry - I took down the website that distributed this code. I'd like to delete this post, so people don't get confused, but stackoverflow won't let me. The stackoverflow error message says, "You cannot delete this accepted answer". – Ribbonwood

Yeah, you can't delete an accepted answer. I guess you could add a warning that the toolbox is no longer available. – Goldshell

Answer 2

You could abuse quiver, this way you don't have to deal with unhandy normalized figure units by use of annotation

drawArrow = @(x,y) quiver( x(1),y(1),x(2)-x(1),y(2)-y(1),0 )    

x1 = [10 30];
y1 = [10 30];

drawArrow(x1,y1); hold on

x2 = [25 15];
y2 = [15 25];

drawArrow(x2,y2)

Important is the 5th argument of quiver: 0 which disables an otherwise default scaling, as this function is actually used to plot vector fields. (or use the poperty value pair 'AutoScale','off')

You can also add additional features:

drawArrow = @(x,y,varargin) quiver( x(1),y(1),x(2)-x(1),y(2)-y(1),0, varargin{:} )       
drawArrow(x1,y1); hold on
drawArrow(x2,y2,'linewidth',3,'color','r')

If you don't like the arrowheads, you need to go back to annotations and this answer is may helpful:

How do I change the arrow head style in quiver plot?

---

Some remarks regarding the comments:

The arrow head size can be adjust with the 'MaxHeadSize' property, it's not consistent unfortunately. The axes limits need to be set afterwards

x1 = [10 30];
y1 = [10 30];
drawArrow(x1,y1,{'MaxHeadSize',0.8,'Color','b','LineWidth',3}); hold on

x2 = [25 15];
y2 = [15 25];
drawArrow(x2,y2,{'MaxHeadSize',10,'Color','r','LineWidth',3}); hold on

xlim([1, 100])
ylim([1, 100])

---

The solution by sed seems to be the best, because it offers adjustable arrow heads.

I'd just would wrap it into a function:

function [ h ] = drawArrow( x,y,xlimits,ylimits,props )

xlim(xlimits)
ylim(ylimits)

h = annotation('arrow');
set(h,'parent', gca, ...
    'position', [x(1),y(1),x(2)-x(1),y(2)-y(1)], ...
    'HeadLength', 10, 'HeadWidth', 10, 'HeadStyle', 'cback1', ...
    props{:} );

end

which you can call from your script as follows:

drawArrow(x1,y1,[1, 100],[1, 100],{'Color','b','LineWidth',3}); hold on
drawArrow(x2,y2,[1, 100],[1, 100],{'Color','r','LineWidth',3}); hold on

giving you quite similar results:

Leatherback

Thanks, But if i want to see the graphs limit (1..100) is it possible ? – Timmerman

add xlim([1, 100]); ylim([1, 100]) just as always – Leatherback

it will work if you write the xlim,ylim after the drawarrow. The only issue is that the arrow head wont look big enough in my view... – Illustrate

@natan you can adjust that by 'MaxHeadSize', see edit. – Leatherback

yes, but the point is that you'll need to play with the proper size for each selection of coordinates and axis limits. In case you'll have limits of [1 10] and arrows from [3 8] you'll get huge arrow heads... So this works great, but you need also to add automatic some arrow head estimator to the solution... something like arrowsize=0.15*abs(diff(xlim).^2+dif(Ylim).^2) – Illustrate

@natan yes I agree, it's just not the best solution ;) – Leatherback

Answer 3

You can use arrow from the file exchange. arrow(Start,Stop) draws a line with an arrow from Start to Stop (points should be vectors of length 2 or 3, or matrices with 2 or 3 columns), and returns the graphics handle of the arrow(s).

Edit: @Lama is also right, you can use annotation but you need to take into account the plot limits.

annotation('arrow',x,y)

creates an arrow annotation object that extends from the point defined by x(1),y(1) to the point defined by x(2),y(2), specified in normalized figure units. You can use the Data space to figure units conversion function (ds2nfu.m) from the file exchange to make your life easier.

[xf yf]=ds2nfu(x,y);
annotation(gcf,'arrow', xf,yf)

Note that there are some undocumented features that allow pinning annotations to graphs if that is needed, read more about it here...

Illustrate

Answer 4

Amongst other solutions, here is one using annotation where you can set the arrow properties including (x,y,width,height) within the current axes, the head and line properties.

h=annotation('arrow');
set(h,'parent', gca, ...
    'position', [50 5 20 2], ...
    'HeadLength', 1000, 'HeadWidth', 100, 'HeadStyle', 'hypocycloid', ...
    'Color', [0.4 0.1 0.8], 'LineWidth', 3);

gives

Rupiah

+1 in my eyes best non-File-Exchange solution. I pimped your idea a little to make it more versatile. – Leatherback

Answer 5

You can also use the following code snippet :

text(x,y,'\leftarrow t_1','FontSize',12,'FontWeight','bold')

Thoroughbred