Box Plots

Usage

boxplot(x, ..., range = 1.5, width = NULL, varwidth = FALSE,
        notch = FALSE, names.x, data = sys.frame(sys.parent()),
        plot = TRUE, border = par("fg"), col = NULL, log = "",
        pars = NULL)

Arguments

x, ... the data from which the boxplots are to be produced. The data can be specified as separate vectors, each corresponding to a component boxplot, or as a single list containing such vectors. Alternatively a symbolic specification of the form x ~ g can be given, indicating that the observations in the vector x are to be grouped according to the levels of the factor g. In this case the argument data can be used to provide values for the variables in the specification. NAs are allowed in the data.
range this determines how far the plot whiskers extend out from the box. If range is positive, the whiskers extend to the most extreme data point which is no more than range times the interquartile range from the box. A value of zero causes the whiskers to extend to the data extremes.
width a vector giving the relative widths of the boxes making up the plot.
varwidth if varwidth is TRUE, the boxes are drawn with widths proportional to the square-roots of the number of observations in the groups.
notch if notch is TRUE, a notch is drawn in each side of the boxes. If the notches of two plots do not overlap then the medians are significantly different at the 5 percent level.
names.x group labels which while be printed under each boxplot.
data data.frame, list, or environment in which variable names are evaluated when x is a formula.
plot if TRUE (the default) then a boxplot is produced. If not, the summaries which the boxplots are based on are returned.
border an optional vector of colors for the outlines of the boxplots. The values in border are recycled if the length of border is less than the number of plots.
col if col is non-null it is assumed to contain colors to be used to col the bodies of the box plots.
log character indicating if x- or y- or both coordinates should be plotted in log scale.
pars, ... graphical parameters can also be passed as arguments to boxplot.

Description

Produce box-and-whisker plot(s) of the given (grouped) values.

Value

List with one component corresponding to each plot. The components are themselves lists with named components as follows:
stats a vector containing the extreme of the lower whisker, the lower hinge, the median, the upper hinge and the extreme of the upper whisker.
n the number of observations in the sample.
conf the lower and upper extremes of the notch.
out the values of any data points which lie beyond the extremes of the whiskers.

See Also

boxplot.stats which does the computation, bxp for the plotting, and stripplot for an alternative (with small data sets).

plot.default for some high-level plotting parameters.

Examples

data(insects)
boxplot(count ~ spray, data = insects, col = "lightgray")

data(bees)
boxplot(decrease ~ treatment, data = bees, log = "y", col="bisque")

## boxplot(.) for a matrix:
mat <- cbind(Uni05= (1:100)/21, Norm= rnorm(100),
             T5 = rt(100,df=5), Gam2= rgamma(100, shape=2))
boxplot(data.frame(mat), main= "boxplot(data.frame(mat), main=...)")

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