R: 1-D Scatter Plots

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 jittering 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 boxplot to current plot.

at

numeric vector giving the locations where the boxplots 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 2.0.0 ]