# plotcorr: Plot correlation matrix ellipses In ellipse: Functions for Drawing Ellipses and Ellipse-Like Confidence Regions

 plotcorr R Documentation

## Plot correlation matrix ellipses

### Description

This function plots a correlation matrix using ellipse-shaped glyphs for each entry. The ellipse represents a level curve of the density of a bivariate normal with the matching correlation.

### Usage

```plotcorr(corr, outline = TRUE, col = 'grey', numbers = FALSE,
type = c("full","lower","upper"),
diag = (type == "full"), bty = "n", axes = FALSE,
xlab = "", ylab = "", asp = 1,
cex.lab = par("cex.lab"), cex = 0.75*par("cex"),
mar = 0.1 + c(2,2,4,2), ...)
```

### Arguments

 `corr` A matrix containing entries between `-1` and `1` to be plotted as correlations. `outline` Whether the ellipses should be outlined in the default colour. `col` Which colour(s) to use to fill the ellipses. `numbers` Whether to plot numerical correlations in place of ellipses. If numbers is `TRUE`, then the correlations will be rounded to a single decimal place and placed on the plot. `type` Character. Plot `"full"` matrix or just `"upper"` or `"lower"` triangular part of it. `diag` Logical. Plot diagonal elements or not. `bty, axes, xlab, ylab, asp, mar, cex.lab, ...` Graphical parameters which will be passed to `plot` when plotting. `cex` Graphical parameter which will be passed to `text` when plotting.

### Details

The ellipses being plotted will be tangent to a unit character square, with the shape chosen to match the required correlation. If `numbers = FALSE`, the `col` vector will be recycled to colour each of the ellipses; if `TRUE`, it will be ignored.

### Author(s)

Duncan Murdoch; Gregor Gorjanc suggested the `type` and `diag` options.

### References

Murdoch, D.J. and Chow, E.D. (1996). A graphical display of large correlation matrices. The American Statistician 50, 178-180. doi: 10.2307/2684435.

`ellipse`

### Examples

```save.par <- par(ask = interactive())

# Plot the correlation matrix for the mtcars data full model fit
data(mtcars)
fit <- lm(mpg ~ ., mtcars)
plotcorr(summary(fit, correlation = TRUE)\$correlation)

# Plot a second figure with numbers in place of the
# ellipses
plotcorr(summary(fit, correlation = TRUE)\$correlation, numbers = TRUE)

# Colour the ellipses to emphasize the differences.  The color range
# is based on RColorBrewer's Reds and Blues (suggested by Gregor Gorjanc)

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])

plotcorr(xc, col=colors[5*xc + 6], type = "upper")
plotcorr(xc, col=colors[5*xc + 6], type = "lower", diag = TRUE)
par(save.par)
```

ellipse documentation built on June 1, 2022, 1:07 a.m.