Ellipses {car} | R Documentation |
These functions draw ellipses, including data ellipses, and confidence ellipses for linear and generalized linear models.
ellipse(center, shape, radius, center.pch=19, center.cex=1.5, segments=51, add=TRUE, xlab="", ylab="", las=par('las'), col=palette()[2], lwd=2, lty=1, ...) data.ellipse(x, y, levels=c(0.5, 0.9), center.pch=19, center.cex=1.5, plot.points=TRUE, add=!plot.points, segments=51, robust=FALSE, xlab=deparse(substitute(x)), ylab=deparse(substitute(y)), las=par('las'), col=palette()[2], pch=1, lwd=2, lty=1, ...) confidence.ellipse(model, ...) ## S3 method for class 'lm': confidence.ellipse(model, which.coef, levels=0.95, Scheffe=FALSE, center.pch=19, center.cex=1.5, segments=51, xlab, ylab, las=par('las'), col=palette()[2], lwd=2, lty=1, ...) ## S3 method for class 'glm': confidence.ellipse(model, which.coef, levels=0.95, Scheffe=FALSE, center.pch=19, center.cex=1.5, segments=51, xlab, ylab, las=par('las'), col=palette()[2], lwd=2, lty=1, ...)
center |
2-element vector with coordinates of center of ellipse. |
shape |
2 * 2 shape (or covariance) matrix. |
radius |
radius of circle generating the ellipse. |
center.pch |
character for plotting ellipse center. |
center.cex |
relative size of character for plotting ellipse center. |
segments |
number of line-segments used to draw ellipse. |
add |
if TRUE add ellipse to current plot. |
xlab |
label for horizontal axis. |
ylab |
label for vertical axis. |
x |
a numeric vector, or (if y is missing) a 2-column numeric matrix. |
y |
a numeric vector, of the same length as x . |
plot.points |
if FALSE data ellipses are added to the current scatterplot,
but points are not plotted. |
levels |
draw elliptical contours at these (normal) probability or confidence levels. |
robust |
if TRUE use the cov.trob function in the MASS package
to calculate the center and covariance matrix for the data ellipse. |
model |
a model object produced by lm or glm . |
which.coef |
2-element vector giving indices of coefficients to plot; if missing, the first two coefficients (disregarding the regression constant) will be selected. |
Scheffe |
if TRUE scale the ellipse so that its projections onto the
axes give Scheffe confidence intervals for the coefficients. |
las |
if 0 , ticks labels are drawn parallel to the
axis; set to 1 for horizontal labels (see par ). |
col |
color for points and lines; the default is the second entry
in the current color palette (see palette
and par ). |
pch |
plotting character for points; default is 1
(a circle, see par ). |
lwd |
line width; default is 2 (see par ). |
lty |
line type; default is 1 , a solid line (see par ). |
... |
other plotting parameters to be passed to plot and
line . |
The ellipse is computed by suitably transforming a unit circle.
data.ellipse
superimposes the normal-probability contours over a scatterplot
of the data.
NULL
. These functions are used for their side effect: producing
plots.
Georges Monette Georges.Monette@mathstat.YorkU.CA and John Fox jfox@mcmaster.ca
Fox, J. (1997) Applied Regression, Linear Models, and Related Methods. Sage.
Monette, G. (1990) Geometry of multiple regression and 3D graphics. In Fox, J. and Long, J. S. (Eds.) Modern Methods of Data Analysis. Sage.
data.ellipse(Prestige$income, Prestige$education, levels=0.1*1:9, lty=2) confidence.ellipse(lm(prestige~income+education, data=Prestige), Scheffe=TRUE)