Thanks,

I ended up adding the R plot as an image to my veusz plot. I then fitted it to 
my X and Y axis and added ellipses on top of the ellipses on the image and then 
removed the R plot image. Not the most elegant  solution but at least the 
result looks perfect.

Johan

-----Original Message-----
From: Veusz-discuss [mailto:[email protected]] On Behalf Of Jeremy 
Sanders
Sent: 15 June 2016 13:29
To: [email protected]
Subject: Re: [Veusz-discuss] adding ellipses to plots

Dear Johan

On 06/15/2016 11:02 AM, Johan Asplund wrote:
> I’m trying to add ellipses to a veusz figure like the one in the 
> attached “plot.png”. The ellipses in plot.png was created using 
> ordielllipse from the R package vegan.

The existing ellipse widget can do something like this. The main problem is 
getting your data into the right form. The ellipse centres can be specified in 
axes coordinates, but unfortunately the width and height and have to be in 
fractions of the plot width. The angle is in degrees. 
This is a pain to compute from your covariance matrix.

However, I think it'd be a good idea to have a direct way of plotting ellipses 
based on covariance matrices. I was thinking of doing something similar for my 
own work. I assume it's mostly a matter of computing the eigenvectors and 
plotting an ellipse/diamond/box aligned along these vectors.

I'll have a think about this. Maybe separate datasets for the items in 
covariance matrix, or using the datasets themselves plus the non-diagnonal 
entry.

Cheers

Jeremy


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