Thanks a lot Rolf, I knew it would be possible to do it that way but I was just curious to know if the ellipse package was offering such a feature. Thanks again for you help!
Antoine Le 28 sept. 11 à 09:30, Rolf Turner-3 [via R] a écrit : > On 28/09/11 04:53, Antoine wrote: > > Dear list members, > > > > This might be a silly question but I just can't figure it out. I > am using > > the "ellipse" package on covariance matrices. I would simply like > to plot my > > ellipses WITH its two axis ploted as well. These axis represents > the 2 eigen > > vectors of my matrix and it is important that I can graphically > show them. > > Is there an easy way to do so? > > Pretty easy. > > * Calculate your eigenvalues and vectors using eigen(). > > * Rescale the vectors by multiplying them by the square > root of the corresponding eigenvalues, and by the constant > corresponding to the confidence level --- e.g. sqrt(qchisq(0.95,2)) > for the usual 95% confidence level. > > * Add these vectors to the ellipse plot, using segments(). > E.g. if your rescaled eigenvectors are v1 and v2, just do: > > segments(-v1[1],-v1[2],v1[1],v1[2]) > > and > > segments(-v2[1],-v2[2],v2[1],v2[2]) > > cheers, > > Rolf Turner > > ______________________________________________ > [hidden email] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > > > If you reply to this email, your message will be added to the > discussion below: > http://r.789695.n4.nabble.com/Adding-axis-to-an-ellipse-ellipse-package-tp3847954p3850233.html > To unsubscribe from Adding axis to an ellipse: "ellipse" package, > click here. -- View this message in context: http://r.789695.n4.nabble.com/Adding-axis-to-an-ellipse-ellipse-package-tp3847954p3850237.html Sent from the R help mailing list archive at Nabble.com. [[alternative HTML version deleted]]
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