## 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

`...` | 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. `NA`s 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`.

## Value

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.

## 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")

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