legendflex: a more flexible legend

Create a legend with more flexible positioning and labeling capabilities

Description

With legendflex, you can:

- position the legend relative to any object in any figure, not just the parent axis of whatever is being labeled
 
- organize legend text and symbols in a grid with a specified number of rows and/or columns

- rescale the horizontal space used by each legend symbol
    
- create multiple legends for the same axis
    
- add a title to the legend within the legend box

• MATLAB release: MATLAB 7.10 (2010a)

[Dan]

 

[Claudio]

Well done! Very useful!

[Jason Kaeding]

Another bug: if I delete the legend then resize my figure, I get an error...

??? Error using ==> getappdata
Invalid object handle

Error in ==> legendflex>resizefig at 621
    Lf = getappdata(ax(ia), 'legflex');
 
??? Error while evaluating figure ResizeFcn

[Jason Kaeding]

I guess it didn't take my first bug submission...

The vertical positioning of the patches is incorrect in the following code:

figure;
area(1:10,rand(10,10))
legendflex(gca,cellstr(num2str(column(1:10))),'ncol',5,'anchor',[6 2],'buffer',[0 -10])

[Kelly Kearney]

Vertical alignment bug has been corrected, and I added some checks to make sure the figure resize doesn't crash when you remove a legend. Thanks to Jason for discovering these bugs.

[Mario Liverpool]

Very useful indeed!

[Philipp]

 

[Ben]

Could you provide the example of getting the result as the screenshoot shows? I think the simple examples in the .m file is not fully demonstrate the capability of your function. Wish you could add more examples.

[Mukhtar Ullah]

This function is the first serious fix to the long lasting problems Matlab has with legends.
The text interpreter is set none by this function and you could only change it when calling the function, and not later using SET. Is there a good reason for that?
Mukhtar

[Kelly Kearney]

@Mukhtar Ullah,

I don't actually manually set the interpreter in this function, so it relies on the default. You can actually change this after the fact using set, as long as you return the object_h handles (see last syntax option); the first n indices of this array will correspond to the n text objects in the legend. This slightly obscure way of returning handles was chosen to be consistent with the original legend command.

[Mukhtar Ullah]

Thank you Kelly for clarifying that. It occurred to me because with legend, it is possible to set properties such as interpreter, string,..using set directly on the axes handle.
A minor addition to legendflex will make it easier to find its handle using findobj and findall function. For example, if you add a tag 'legendflex' to the axes, findobj(gcf, 'tag', 'legendflex') would locate the axes.

Mukhtar

[Mukhtar Ullah]

I just realized that it is possible to find the legendflex axes by
ax = getappdata(hfig, 'legflexchildren')
I now have another problem. When I use legendflex together with panel
http://www.mathworks.co.uk/matlabcentral/fileexchange/20003-panel
any attempt to resize the figure results in the following error
Error using panel.resizeCallback
Cannot access method 'resizeCallback' in class 'panel'.

Error in legendflex>resizefig (line 637)
                feval(Lf.oldrsz, hfig, ed);
 
Error using drawnow
Error while evaluating figure ResizeFcn

It turned out that commenting line 637 solves my problem.
Any idea of fixing this in a future release?

Thanks

[Kelly Kearney]

@Mukhtar Ullah

Regarding making legendflex play nicely with panel, I admit I never considered the possibility that a figure's resize function might be linked to an object method. I don't do object-oriented coding myself, so I have very little knowledge of the internal workings, scope, etc. of objects. So no promises to fix this, though I will look into it if I find some spare time.

[Mukhtar Ullah]

Thanks Kelly for your explanation. I am not sure what will I loose if I keep those lines commented out. At the moment, I am avoiding any figure resize when both legendflex and panel are at play.
 

[Camille Couzi]

thanks a lot for this very useful code!!!

[Dominic]

 

[Chris]

Very nice - thanks!
I wonder if anyone knows how to go a step beyond. That is, my legends are often like tables which I currently hand make as figures within figures. The table-like legend has row and column headings with only the symbols/line types in the cells instead of a label for every symbol/line. This is because the symbol itself might change to represent one variable and whether it's filled or open might represent another so it's identity is a combination of the row and column headings in the table.