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 _______________________________________________ Veusz-discuss mailing list [email protected] https://mail.gna.org/listinfo/veusz-discuss
