stripchart {graphics}R Documentation

1-D Scatter Plots

Description

stripchart produces one dimensional scatter plots (or dot plots) of the given data. These plots are a good alternative to boxplots when sample sizes are small.

Usage

stripchart(x, ...)

## S3 method for class 'formula':
stripchart(x, data = NULL, dlab = NULL, ...,
           subset, na.action = NULL)

## Default S3 method:
stripchart(x, method = "overplot", jitter = 0.1, offset = 1/3,
           vertical = FALSE, group.names, add = FALSE,
           at = NULL, xlim = NULL, ylim = NULL,
           ylab=NULL, xlab=NULL, dlab="", glab="",
           log = "", pch = 0, col = par("fg"), cex = par("cex"), 
           axes = TRUE, frame.plot = axes, ...)

Arguments

x the data from which the plots are to be produced. In the default method the data can be specified as a single numeric vector, or as list of numeric vectors, each corresponding to a component plot. In the formula method, a symbolic specification of the form y ~ g can be given, indicating the observations in the vector y are to be grouped according to the levels of the factor g. NAs are allowed in the data.
data a data.frame (or list) from which the variables in x should be taken.
subset an optional vector specifying a subset of observations to be used for plotting.
na.action a function which indicates what should happen when the data contain NAs. The default is to ignore missing values in either the response or the group.
... additional parameters passed to the default method, or by it to plot, axis and title to control the appearance of the plot.
method the method to be used to separate coincident points. The default method "overplot" causes such points to be overplotted, but it is also possible to specify "jitter" to jitter the points, or "stack" have coincident points stacked. The last method only makes sense for very granular data.
jitter when method="jitter" is used, jitter gives the amount of jittering applied.
offset when stacking is used, points are stacked this many line-heights (symbol widths) apart.
vertical when vertical is TRUE the plots are drawn vertically rather than the default horizontal.
group.names group labels which will be printed alongside (or underneath) each plot.
add logical, if true add the chart to the current plot.
at numeric vector giving the locations where the charts should be drawn, particularly when add = TRUE; defaults to 1:n where n is the number of boxes.
ylab, xlab labels: see title.
dlab, glab alternate way to specify axis labels: see ‘Details’.
xlim, ylim plot limits: see plot.window.
log on which axes to use a log scale: see plot.default
pch, col, cex Graphical parameters: see par.
axes, frame.plot Axis control: see plot.default

Details

Extensive examples of the use of this kind of plot can be found in Box, Hunter and Hunter or Seber and Wild.

The dlab and glab labels may be used instead of xlab and ylab if those are not specified. dlab applies to the continuous data axis (the X axis unless vertical is TRUE), glab to the group axis.

Examples

x <- stats::rnorm(50)
xr <- round(x, 1)
stripchart(x) ; m <- mean(par("usr")[1:2])
text(m, 1.04, "stripchart(x, \"overplot\")")
stripchart(xr, method = "stack", add = TRUE, at = 1.2)
text(m, 1.35, "stripchart(round(x,1), \"stack\")")
stripchart(xr, method = "jitter", add = TRUE, at = 0.7)
text(m, 0.85, "stripchart(round(x,1), \"jitter\")")

stripchart(decrease ~ treatment,
    main = "stripchart(OrchardSprays)", 
    vertical = TRUE, log = "y", data = OrchardSprays)

stripchart(decrease ~ treatment, at = c(1:8)^2,
    main = "stripchart(OrchardSprays)", 
    vertical = TRUE, log = "y", data = OrchardSprays)

[Package graphics version 2.8.0 Index]