Ellipses {car} | R Documentation |
These functions draw ellipses, including data ellipses, and confidence ellipses for linear and generalized linear models.
ellipse(center, shape, radius, log="", center.pch=19, center.cex=1.5, segments=51, add=TRUE, xlab="", ylab="", col=palette()[2], lwd=2, fill=FALSE, fill.alpha=0.3, grid=TRUE, ...) dataEllipse(x, y, log="", levels=c(0.5, 0.95), 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)), col=palette()[1:2], lwd=2, fill=FALSE, fill.alpha=0.3, grid=TRUE, ...) confidenceEllipse(model, ...) ## S3 method for class 'lm' confidenceEllipse(model, which.coef, levels=0.95, Scheffe=FALSE, center.pch=19, center.cex=1.5, segments=51, xlab, ylab, col=palette()[2], lwd=2, fill=FALSE, fill.alpha=0.3, add=FALSE, ...) ## S3 method for class 'glm' confidenceEllipse(model, which.coef, levels=0.95, Scheffe=FALSE, center.pch=19, center.cex=1.5, segments=51, xlab, ylab, col=palette()[2], lwd=2, fill=FALSE, fill.alpha=0.3, add=FALSE, ...)
center |
2-element vector with coordinates of center of ellipse. |
shape |
2 * 2 shape (or covariance) matrix. |
radius |
radius of circle generating the ellipse. |
log |
when an ellipse is to be added to an existing plot, indicates
whether computations were on logged values and to be plotted on logged
axes; "x" if the x-axis is logged, "y" if the y-axis is
logged, and "xy" or "yx" if both axes are logged. The
default is "" , indicating that neither axis is logged. |
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. |
col |
color for lines and ellipse center; the default is the second entry
in the current color palette (see palette
and par ). For dataEllipse , two colors can be given, in
which case the first is for plotted points and the second for lines and the ellipse center. |
lwd |
line width; default is 2 (see par ). |
fill |
fill the ellipse with translucent color col (default, FALSE )? |
fill.alpha |
transparency of fill (default = 0.3 ). |
... |
other plotting parameters to be passed to plot and
line . |
grid |
If TRUE, the default, a light-gray background grid is put on the graph |
The ellipse is computed by suitably transforming a unit circle.
dataEllipse
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. (2008) Applied Regression Analysis and Generalized Linear Models, Second Edition. Sage.
Fox, J. and Weisberg, S. (2011) An R Companion to Applied Regression, Second Edition, 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.
dataEllipse(Prestige$income, Prestige$education, levels=0.1*1:9, lty=2, fill=TRUE, fill.alpha=0.1) confidenceEllipse(lm(prestige~income+education, data=Prestige), Scheffe=TRUE)