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Box Plots

Syntax

boxplot(..., range=1.5, width, varwidth=FALSE,
        notch=FALSE, names, data, plot=TRUE, col=NULL,
        border=par("fg"))

Arguments

... 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 the 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.
name group labels which while be printed under each boxplot.
plot if plot is 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.
... graphical parameters can also be passed as arguments to boxplot.

Values

This function is usually invoked for its side effect which is to produce box-and-whisker plots of the given values. However, it also returns a 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(insects) boxplot(count~spray, data=insects, col="lightgray")