car (version 2.1-3)

scatterplot: Scatterplots with Boxplots

Description

Makes enhanced scatterplots, with boxplots in the margins, a nonparametric regression smooth, smoothed conditional spread, outlier identification, and a regression line; sp is an abbreviation for scatterplot.

Usage

scatterplot(x, ...)
"scatterplot"(formula, data, subset, xlab, ylab, legend.title, legend.coords,
	labels, ...)
"scatterplot"(x, y,  smoother=loessLine, smoother.args=list(), smooth, span, spread=!by.groups, reg.line=lm, boxplots=if (by.groups) "" else "xy", xlab=deparse(substitute(x)), ylab=deparse(substitute(y)), las=par("las"), lwd=1, lty=1, labels, id.method = "mahal",  id.n = if(id.method[1]=="identify") length(x) else 0,  id.cex = 1, id.col = palette()[1], id.location="lr", log="", jitter=list(), xlim=NULL, ylim=NULL, cex=par("cex"), cex.axis=par("cex.axis"), cex.lab=par("cex.lab"),  cex.main=par("cex.main"), cex.sub=par("cex.sub"),  groups, by.groups=!missing(groups),  legend.title=deparse(substitute(groups)), legend.coords, legend.columns, ellipse=FALSE, levels=c(.5, .95), robust=TRUE, col=if (n.groups == 1) palette()[3:1] else rep(palette(), length=n.groups), pch=1:n.groups,  legend.plot=!missing(groups), reset.par=TRUE, grid=TRUE, ...)
sp(x, ...)

Arguments

x

vector of horizontal coordinates (or first argument of generic function).

y

vector of vertical coordinates.

formula

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.

data

data frame within which to evaluate the formula.

subset

expression defining a subset of observations.

smoother

a function to draw a nonparametric-regression smooth; the default is loessLine, which does loess smoothing. The function gamLine fits a generalized additive model and allows including a link and error function. See ScatterplotSmoothers. Setting this argument to something other than a function, e.g., FALSE suppresses the smoother.

smoother.args

a list of named values to be passed to the smoother function; the specified elements of the list depend upon the smoother (see ScatterplotSmoothers).

smooth, span

these arguments are included for backwards compatility: if smooth=TRUE then smoother is set to loessLine, and if span is specified, it is added to smoother.args.

spread

if TRUE, estimate the (square root) of the variance function. For loessLine and for gamLine, this is done by separately smoothing the squares of the postive and negative residuals from the mean fit, and then adding the square root of the fitted values to the mean fit. For quantregLine, fit the .25 and .75 quantiles with a quantile regression additive model. The default is TRUE if by.groups=FALSE and FALSE is by.groups=TRUE.

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).

lty

type of linear-regression lines (default 1, solid line).

id.method,id.n,id.cex,id.col,id.location

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; can 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.

legend.columns

number of columns for the legend; if absent will be supplied automatically to prefer horizontal legends when plotted above the graph.

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()[3] for linear regression lines, palette()[2] for nonparametric regression lines, and palette()[1] for 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.

See Also

boxplot, jitter, legend, scatterplotMatrix, dataEllipse, Boxplot, cov.trob, showLabels, ScatterplotSmoothers.

Examples

scatterplot(prestige ~ income, data=Prestige, ellipse=TRUE)

if (interactive()){
scatterplot(prestige ~ income, data=Prestige, smoother=quantregLine)
}

scatterplot(prestige ~ income|type, data=Prestige, smoother=loessLine, 
    smoother.args=list(span=1))

scatterplot(prestige ~ income|type, data=Prestige, legend.coords="topleft")

scatterplot(vocabulary ~ education, jitter=list(x=1, y=1), 
	data=Vocab, id.n=0, smoother=FALSE)

scatterplot(infant.mortality ~ gdp, log="xy", data=UN, id.n=5)

scatterplot(income ~ type, data=Prestige)

	## Not run: 
# scatterplot(infant.mortality ~ gdp, id.method="identify", data=UN)
# 
# scatterplot(infant.mortality ~ gdp, id.method="identify", smoother=loessLine, data=UN)
# 	## End(Not run)