Description Usage Arguments Details Value Author(s) References See Also Examples
These functions draw ellipses, including data ellipses, and confidence ellipses for linear, generalized linear, and possibly other models.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | ellipse(center, shape, radius, log="", center.pch=19, center.cex=1.5,
segments=51, draw=TRUE, add=draw, xlab="", ylab="",
col=palette()[2], lwd=2, fill=FALSE, fill.alpha=0.3, grid=TRUE, ...)
dataEllipse(x, y, groups, group.labels = group.levels, ellipse.label,
weights, log = "", levels = c(0.5, 0.95), center.pch = 19,
center.cex = 1.5, draw = TRUE, plot.points = draw, add = !plot.points,
segments = 51, robust = FALSE, xlab = deparse(substitute(x)),
ylab = deparse(substitute(y)),
col = if (missing(groups)) palette()[1:2] else palette()[1:length(group.levels)],
pch = if (missing(groups)) 1 else seq(group.levels), lwd = 2,
fill = FALSE, fill.alpha = 0.3, grid = TRUE, labels, id.method = "mahal",
id.n = if (id.method[1] == "identify") Inf else 0, id.cex = 1,
id.col = if (missing(groups)) palette()[1] else palette()(1:length(groups)),
id.location="lr", ...)
confidenceEllipse(model, ...)
## S3 method for class 'lm'
confidenceEllipse(model, which.coef, L, levels=0.95, Scheffe=FALSE, dfn,
center.pch=19, center.cex=1.5, segments=51, xlab, ylab,
col=palette()[2], lwd=2, fill=FALSE, fill.alpha=0.3, draw=TRUE, add=!draw, ...)
## S3 method for class 'glm'
confidenceEllipse(model, chisq, ...)
## Default S3 method:
confidenceEllipse(model, which.coef, L, levels=0.95, Scheffe=FALSE, dfn,
center.pch=19, center.cex=1.5, segments=51, xlab, ylab,
col=palette()[2], lwd=2, fill=FALSE, fill.alpha=0.3, draw=TRUE, add=!draw, ...)
|
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; |
center.pch |
character for plotting ellipse center; if |
center.cex |
relative size of character for plotting ellipse center. |
segments |
number of line-segments used to draw ellipse. |
draw |
if |
add |
if |
xlab |
label for horizontal axis. |
ylab |
label for vertical axis. |
x |
a numeric vector, or (if |
y |
a numeric vector, of the same length as |
groups |
optional: a factor to divide the data into groups; a separate ellipse will be plotted for each group (level of the factor). |
group.labels |
labels to be plotted for the groups; by default, the levels of the |
ellipse.label |
a label for the ellipse(s) or a vector of labels; if several ellipses are drawn and just one label is given, then that label will be repeated. The default is not to label the ellipses. |
weights |
a numeric vector of weights, of the same length as |
plot.points |
if |
levels |
draw elliptical contours at these (normal) probability or confidence levels. |
robust |
if |
model |
a model object produced by |
which.coef |
2-element vector giving indices of coefficients to plot; if missing, the first two coefficients (disregarding the regression constant) will be selected. |
L |
As an alternative to selecting coefficients to plot, a transformation matrix can be specified to compute two
linear combinations of the coefficients; if the |
Scheffe |
if |
dfn |
“numerator” degrees of freedom (or just degrees of freedom for a GLM) for
drawing the confidence ellipse. Defaults to the number of coefficients in the model (disregarding the constant) if
|
chisq |
if |
col |
color for lines and ellipse center; the default is the second entry
in the current color palette (see |
pch |
for |
lwd |
line width; default is |
fill |
fill the ellipse with translucent color |
fill.alpha |
transparency of fill (default = |
... |
other plotting parameters to be passed to |
labels,id.method,id.n,id.cex,id.col,id.location |
Arguments for the labelling of
points. The default is |
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.
These functions are mainly used for their side effect of producing plots. For
greater flexibility (e.g., adding plot annotations), however, ellipse
returns invisibly the (x, y) coordinates of the calculated ellipse.
dataEllipse
and confidenceEllipse
return invisibly the coordinates of one or more ellipses, in the latter instance a list named by
levels
.
Georges Monette, John Fox jfox@mcmaster.ca, and Michael Friendly.
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.
cov.trob
, cov.wt
, linearHypothesis
.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | dataEllipse(Duncan$income, Duncan$education, levels=0.1*1:9,
ellipse.label=0.1*1:9, lty=2, fill=TRUE, fill.alpha=0.1)
confidenceEllipse(lm(prestige~income+education, data=Duncan), Scheffe=TRUE)
confidenceEllipse(lm(prestige~income+education, data=Duncan),
L=c("income + education", "income - education"))
wts <- rep(1, nrow(Duncan))
wts[c(6, 16)] <- 0 # delete Minister, Conductor
with(Duncan, {
dataEllipse(income, prestige, levels=0.68)
dataEllipse(income, prestige, levels=0.68, robust=TRUE, plot.points=FALSE, col="green3")
dataEllipse(income, prestige, weights=wts, levels=0.68, plot.points=FALSE, col="brown")
dataEllipse(income, prestige, weights=wts, robust=TRUE, levels=0.68,
plot.points=FALSE, col="blue")
})
with(Prestige, dataEllipse(income, education, type, id.n=2, pch=15:17,
labels=rownames(Prestige), xlim=c(0, 25000), center.pch="+",
group.labels=c("Blue Collar", "Professional", "White Collar"),
ylim=c(5, 20), level=.95, fill=TRUE, fill.alpha=0.1))
|
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