R: Box Plots

boxplot.default {base}

R Documentation

Box Plots

Description

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

Usage

boxplot.default(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

group labels which will 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.

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.

Examples

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

data(OrchardSprays)
boxplot(decrease ~ treatment, data = OrchardSprays, 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=...)")