Functions for Drawing Ellipses and Ellipse-Like Confidence Regions

Contains various routines for drawing ellipses and ellipse-like confidence regions, implementing the plots described in Murdoch and Chow (1996, ). There are also routines implementing the profile plots described in Bates and Watts (1988, ).

ellipse

ellipse contains ellipse drawing routines designed for pairwise confidence regions, including distorted ellipses for nonlinear regression regions. It also includes a routine plotcorr() for plotting correlation matrices using ellipses.

Installation

It is on CRAN, and can be installed using

install.packages("ellipse")

You can install the development version of ellipse from GitHub with:

# install.packages("devtools")
devtools::install_github("dmurdoch/ellipse")

Example

Plot approximate pairwise confidence regions and profile trace plots for a nonlinear fit:

data(Puromycin)
Purboth <- nls(formula = rate ~ ((Vm + delV * (state == "treated"))
   * conc)/(K + conc), data = Puromycin,
   start = list(Vm = 160, delV = 40, K = 0.05))
Pur.prof <- profile(Purboth)
ellipse::pairs(Pur.prof)

The plotcorr() function can plot a matrix of ellipses:

library(ellipse)
#> 
#> Attaching package: 'ellipse'
#> The following object is masked from 'package:graphics':
#> 
#>     pairs
corr.mtcars <- cor(mtcars)
ord <- order(corr.mtcars[1,])
xc <- corr.mtcars[ord, ord]
colors <- c("#A50F15","#DE2D26","#FB6A4A","#FCAE91","#FEE5D9","white",
            "#EFF3FF","#BDD7E7","#6BAED6","#3182BD","#08519C")   
plotcorr(xc, col=colors[5*xc + 6])