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, method = "overplot", jitter = 0.1, offset = 1/3,
           vertical = FALSE, group.names, add = FALSE,
           at = NULL, xlim = NULL, ylim = NULL,
           main = "", ylab = "", xlab = "",
           log = "", pch = 0, col = par("fg"), cex = par("cex"))

Arguments

x the data from which the plots are to be produced. The data can be specified as a single vector, or as list of vectors, each corresponding to a component plot. Alternatively a symbolic specification of the form x ~ g can be given, indicating the the observations in the vector x are to be grouped according to the levels of the factor g. NAs are allowed in the data.
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.
xlim, ylim, main, ylab, xlab, log, pch, col, cex Graphical parameters.

Details

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

Examples

x <- 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\")")

with(OrchardSprays,
     stripchart(decrease ~ treatment,
                main = "stripchart(Orchardsprays)", ylab = "decrease",
                vertical = TRUE, log = "y"))

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

[Package graphics version 2.1.0 Index]