[R] adding an ellipse to a PCA plot

[Alain Guillet]

Hi,

I think the easiest way is to use the function plotellipses of the 
FactoMineR package (but you have to do your PCA with the PCA function 
included in this package).

Alain

On 06-Jun-11 16:32, Lukas Baitsch wrote:
> Hi,
>
> I created a principal component plot using the first two principal
> components. I used the function princomp() to calculate the scores.
> now, I would like to superimpose an ellipse representing the center
> and the 95% confidence interval of a series of points in my plot (as
> to illustrate the grouping of my samples).
>
> I looked at the ellipse() function in the ellipse package but can't
> get it to work. the princomp()-function gives me the scores of each
> point, so I can calculate the mean and the 95%-CI, but I can't
> integrate this into the ellipse()-function). Is there a better way of
> doing this or can someone help me figure out this function?
>
> best regards,
>
> Lukas
>
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-- 
Alain Guillet
Statistician and Computer Scientist

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