README.Rmd

---
output: github_document
---

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```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.path = "man/figures/README-",
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)
```

# ellipse

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`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

``` r
install.packages("ellipse")
```

You can install the development version of ellipse from [GitHub](https://github.com/) with:

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

## Example

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

```{r pairs.profile}
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:

```{r plotcorr}
library(ellipse)
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])
```