A minor modification of the car package's scatterplot function that makes enhanced scatterplots, with boxplots in the margins, a lowess
smooth, smoothed conditional spread, outlier identification, and a regression line; sp is an abbreviation for
scatterplot.
vector of horizontal coordinates, or a “model” formula, of the form y ~ x or
(to plot by groups) y ~ x | z, where z evaluates to a factor
or other variable dividing the data into groups. If x is a factor, then parallel boxplots
are produced using the Boxplot function.
y
vector of vertical coordinates.
data
data frame within which to evaluate the formula.
subset
expression defining a subset of observations.
smooth
if TRUE (the default) a loess nonparametric regression line is
drawn on the plot.
spread
if TRUE (the default when there are no groups), a smoother is applied to
the root-mean-square positive and negative residuals from the loess line to display conditional spread and
asymmetry.
span
span for the loess smoother.
loess.threshold
suppress the loess smoother if there are fewer than loess.threshold unique
values (default, 5) of y.
reg.line
function to draw a regression line on the plot
or FALSE not to plot a regression line.
boxplots
if "x" a boxplot for x is drawn below the plot;
if "y" a boxplot for y is drawn to the left of the plot;
if "xy" both boxplots are drawn; set to "" or FALSE to
suppress both boxplots.
xlab
label for horizontal axis.
ylab
label for vertical axis.
las
if 0, ticks labels are drawn parallel to the
axis; set to 1 for horizontal labels (see par).
lwd
width of linear-regression lines (default 1).
lwd.smooth
width for smooth regression lines (default is the same as lwd).
lwd.spread
width for lines showing spread (default is the same as lwd).
lty
type of linear-regression lines (default 1, solid line).
lty.smooth
type of smooth regression lines (default is the same as lty).
lty.spread
width for lines showing spread (default is 2, broken line).
id.method,id.n,id.cex,id.col
Arguments for the labelling of
points. The default is id.n=0 for labeling no points. See
showLabels for details of these arguments. If the plot uses
different colors for groups, then the id.col argument is ignored and
label colors are determined by the col argument.
labels
a vector of point labels; if absent, the function tries to determine reasonable
labels, and, failing that, will use observation numbers.
log
same as the log argument to plot, to produce log axes.
jitter
a list with elements x or y or both, specifying jitter factors
for the horizontal and vertical coordinates of the points in the scatterplot. The
jitter function is used to randomly perturb the points; specifying a
factor of 1 produces the default jitter. Fitted lines are unaffected by the jitter.
xlim
the x limits (min, max) of the plot; if NULL, determined from the data.
ylim
the y limits (min, max) of the plot; if NULL, determined from the data.
groups
a factor or other variable dividing the data into groups; groups are
plotted with different colors and plotting characters.
by.groups
if TRUE, regression lines are fit by groups.
legend.title
title for legend box; defaults to the name of the groups variable.
legend.coords
coordinates for placing legend; an be a list with components x and y to
specify the coordinates of the upper-left-hand corner of the legend; or a quoted keyword, such as "topleft",
recognized by legend.
ellipse
if TRUE data-concentration ellipses are plotted.
levels
level or levels at which concentration ellipses are plotted;
the default is c(.5, .95).
robust
if TRUE (the default) use the cov.trob function in the MASS package
to calculate the center and covariance matrix for the data ellipses.
col
colors for lines and points; the default is taken from the color palette,
with palette()[2] for nonparametric regression lines and palette()[1]
for linear regression line and points if there are
no groups, and successive colors for the groups if there are groups.
pch
plotting characters for points; default is the plotting characters in
order (see par).
cex, cex.axis, cex.lab, cex.main, cex.sub
set sizes of various graphical elements;
(see par).
legend.plot
if TRUE then a legend for the groups is plotted in the upper margin.
reset.par
if TRUE then plotting parameters are reset to their previous values
when scatterplot exits; if FALSE then the mar and mfcol parameters are
altered for the current plotting device. Set to FALSE if you want to add graphical elements
(such as lines) to the plot.
...
other arguments passed down and to plot.
grid
If TRUE, the default, a light-gray background grid is put on the
graph
Value
If points are identified, their labels are returned; otherwise NULL is returned invisibly.