bxp                 package:graphics                 R Documentation

Box Plots from Summaries

Description:

     'bxp' draws box plots based on the given summaries in 'z'. It is
     usually called from within 'boxplot', but can be invoked directly.

Usage:

     bxp(z, notch = FALSE, width = NULL, varwidth = FALSE, outline = TRUE,
         notch.frac = 0.5, boxwex = 0.8, border = par("fg"), col = NULL,
         log = "", pars = NULL, frame.plot = axes, horizontal = FALSE,
         add = FALSE, at = NULL, show.names=NULL, ...)

Arguments:

       z: a list containing data summaries to be used in constructing
          the plots.  These are usually the result of a call to
          'boxplot', but can be generated in any fashion.

   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.

   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.

 outline: if 'outline' is not true, the boxplot lines are not drawn.

  boxwex: a scale factor to be applied to all boxes.  When there are
          only a few groups, the appearance of the plot can be improved
          by making the boxes narrower.

notch.frac: numeric in (0,1). When 'notch=TRUE', the fraction of the
          box width that the notches should use.

  border: character, the color of the box borders.  Is recycled for
          multiple boxes.

     col: character; the color within the box.  Is recycled for
          multiple boxes

     log: character, indicating if any axis should be drawn in
          logarithmic scale, as in 'plot.default'.

frame.plot: logical, indicating if a "frame" ('box') should be drawn;
          defaults to 'TRUE', unless 'axes = FALSE' is specified.

horizontal: logical indicating if the  boxplots should be horizontal;
          default 'FALSE' means vertical boxes.

     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.

show.names: Set to 'TRUE' or 'FALSE' to override the defaults on
          whether an x-axis label is printed for each group.

pars,...: graphical parameters can be passed as arguments to this
          function, either as a list ('pars') or normally('...').

          Currently, 'pch', 'cex', and 'bg' are passed to 'points',
           'ylim' and 'axes' to the main plot ('plot.default'), 'xaxt',
          'yaxt', 'las' to 'axis' and the others to 'title'. 

Value:

     An invisible vector, actually identical to the 'at' argument, with
     the coordinates ("x" if horizontal is false, "y" otherwise) of box
     centers, useful for adding to the plot.

References:

     Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) _The New S
     Language_. Wadsworth & Brooks/Cole.

Examples:

     set.seed(753)
     (bx.p <- boxplot(split(rt(100, 4), gl(5,20))))
     op <- par(mfrow= c(2,2))
     bxp(bx.p, xaxt = "n")
     bxp(bx.p, notch = TRUE, axes = FALSE, pch = 4)
     bxp(bx.p, notch = TRUE, col= "lightblue", frame= FALSE, outl= FALSE,
         main = "bxp(*, frame= FALSE, outl= FALSE)")
     bxp(bx.p, notch = TRUE, col= "lightblue", border="red", ylim = c(-4,4),
         pch = 22, bg = "green", log = "x", main = "... log='x', ylim=*")
     par(op)
     op <- par(mfrow= c(1,2))
     data(PlantGrowth)
     ## single group -- no label
     boxplot(weight~group,data=PlantGrowth,subset=group=="ctrl")
     bx<-boxplot(weight~group,data=PlantGrowth,subset=group=="ctrl",plot=FALSE)
     ## with label
     bxp(bx,show.names=TRUE)
     par(op)

