fields (version 1.2)

bplot: boxplot

Description

Plots boxplots of several groups of data and allows for placement at different horizontal or vertical positions. It is also flexible in the input object accepting either a list or matrix.

Usage

bplot(x, by,style = "tukey", outlier = TRUE, plot = TRUE, ...)

Arguments

x

Vector, matrix, list or data frame. A vector may be divided according to the by argument. Matrices and data frames are separated by columns and lists by components.

by

If x is a vector, an optional vector (either character or numerical) specifying the categories to divide x into separate data sets.

style

Type of boxplot default is "tukey". The other choice is "quantile" where the whiskers are drawn to the 5 and 95 percentiles instead being based on the inner fences.

outlier

If true outliers (points beyond outer fences) will be added to the plots.

plot

If false just returns a list with the statistics used for plotting the box plots.

...

Other arguments controlling the boxplots ( passed to bplot.obj) these are listed below. Other graphical plotting arguments not matched (e.g. yaxt) are used in the call to plot to set up the intial plot if add=T.

pos

The boxplots will be plotted vertically and pos gives the x or y locations for their centers. If omitted the boxes are equally spaced at integer values.

width

Width of boxplots (in user coordinates) if omitted then the width is a reasonable fraction of the distance between boxes and is set by the space argument.

labels

Labels under each boxplot. If missing the columns names or components of x are used.

srt

Rotate the labels (srt=90 makes them vertical). Default is to put them horizontal. Sometimes long labels run into each if they are horizontal.

add

If true, do not create a new plots just add the boxplots to a current plot. Note that the pos argument may be useful in this case and should be in the user coordinates of the parent plot.

space

Space between boxplots.

sort.names

If true plot the boxplot data set names are sorted in alphabetic order by their labels.

xlab

Label for the x-axis

ylab

Label for the y-axis

label.cex

Boxplot label size where 1.0 is normal size characters. If zero labels will not be added.

xaxt

Plotting parameter for x-axis generation. Default is not to produce an x-axis.

horizontal

If true draw boxplots horizontally the default is false, produce veritcal box plots.

Details

This function was created as a complement to the usual S function for boxplots. The current function makes it possible to put the boxplots at unequal x or y positions. This is useful for visually grouping a large set of boxplots into several groups. Also placement of the boxplots with respect to the axis can add information to the plot. Another aspect is the emphasis on data structures for groups of data. One useful feature is the by option to break up the x vector into distinct groups. If 5 or less observations are in a group the points themselves are plotted instead of a box.

The function is broken into two steps: a call to stats.bplot to find the statistics and a call to bplot.obj to plot the resulting object. The user is referred to describe.bplot to modify the statistics used and to draw.bplot.obj to modify how the bplot is drawn.

Finally to bin data into groups based on a continuous variable and to make bplots of each group see bplot.xy.

See Also

describe.bplot, draw.bplot.obj, stats.bplot, bplot.xy, bplot.obj

Examples

#
set.seed(123)
temp<- matrix( rnorm(12*8), ncol=12)
pos<- c(1:6,9:14)
bplot(temp)
#
bplot( temp, pos=pos, labels=paste( "D",1:12), horizontal=TRUE)
#
bplot( temp, pos=pos, label.cex=0, horizontal=TRUE)
# add an axis
axis( 2)