boxplotlog: Boxplotlog

In StatDA: Statistical Analysis for Environmental Data

Boxplotlog

Description

The function boxplot plots a boxplot of the data with respect to the logarithmic transformed values of the whiskers. See also details.

Usage

boxplotlog(x, ..., range = 1.5, width = NULL, varwidth = FALSE, notch = FALSE,
outline = TRUE, names, plot = TRUE, border = par("fg"), col = NULL, log = "",
pars = list(boxwex = 0.8, staplewex = 0.5, outwex = 0.5), horizontal = FALSE,
add = FALSE, at = NULL)

Arguments

x	data
...	further arguments for creating the list
range	this determines how far the plot "whiskers" extend from the box. If range is positive, the most extreme data point which is no more than range times the length of the box away 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
outline	if outline is FALSE, the outliers are not drawn
names	define the names of the attributes
plot	if plot is TRUE the boxplot is plotted in the current plot
border	character or numeric (vector) which indicates the color of the box borders
col	defines the colour
log	character, indicating if any axis should be drawn in logarithmic scale
pars	some graphical parameters can be specified
horizontal	logical parameter indicating if the boxplots should be horizontal; FALSE means vertical boxes
add	if TRUE the boxplot is added to the current plot
at	numeric vector giving the locations of the boxplots

Details

Sometimes a boxplot of the original data does not identify outliers because the boxplot assumes normal distribution. Therefore the data are logarithmically transformed and values for plotting the boxplot are calculated. After that the data are backtransformed and the boxplot is plotted with respect to the logarithmic results. Now the outliers are identified.

Value

stats	a vector of length 5, containing the extreme of the lower whisker, the lower "hinge", the median, the upper "hinge" and the extreme of the upper whisker (backtransformed)
n	the number of non-NA 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 (backtransformed)
group	the group
names	the attributes

Returns a boxplot which is calculated with the log-transformed data.

Author(s)

Peter Filzmoser <[e-mail]> http://cstat.tuwien.ac.at/filz/

References

C. Reimann, P. Filzmoser, R.G. Garrett, and R. Dutter: Statistical Data Analysis Explained. Applied Environmental Statistics with R. John Wiley and Sons, Chichester, 2008.

Examples

data(chorizon)
Ba=chorizon[,"Ba"]

boxplotlog((Ba),horizontal=TRUE,xlab="Ba [mg/kg]",cex.lab=1.4,pch=3,cex=1.5)

StatDA documentation built on June 7, 2023, 6:26 p.m.