Boxplots From Processed Data

DESCRIPTION:

Creates boxplots on the current graphics device from a list that describes the boxplots explicitly.

USAGE:

bxp(z, width=<<see below>>, varwidth=F, notch=F, style.bxp=list(), 
    boxwex=.5, boxcol=3, medchar=F, medpch=NA, medline=T, medlwd=5, 
    medcol=0, confint=F, confcol=2, confangle=45, confdensity=25, 
    confnotch=F, whisklty=2, staplelty=1, staplewex=1, staplehex=1, 
    outchar=F, outpch=NA, outline=T, outwex=1, ...) 

REQUIRED ARGUMENTS:

z
list whose components define the boxplot statistics, normally the result of a call to boxplot but can be built up in any other way. See boxplot for a description of the necessary components of z.

OPTIONAL ARGUMENTS:

width
vector of box widths. The widths are all the same by default.
varwidth
logical flag: if TRUE, variable width boxes are drawn proportional to the square root of z$n.
notch
logical flag: if TRUE, use the z$conf to produce notched boxplots. (NOTE: The notch parameter is provided primarily for backward compatibility. See the confint, confnotch, confcol, confangle and confdensity parameters below for more versatile control of the displaying of confidence intervals.)
style.bxp
character string or list indicating the style of the boxplot. If specified as a character string, the string is appended to " bxp." to get the name of a dataset which is a list. Component names of this list should match the names of the parameters below; the component values serve as the defaults for the corresponding parameters (i.e., other arguments supplied to the function override the style.bxp component values). Standard style.bxp option values include "splus" (new S-PLUS style), "att" (new AT&T style) and "old".
boxwex
box width expansion. The width of the boxes, along with the width of the staples (whisker end caps) and outliers (if drawn as lines), are proportional to this parameter. The default is 0.5, but the "att" and "old" styles set this to 1.
border
logical flag that specifies whether the border of the boxplot will be drawn. Border can also be specified as a single color value or a vector of color values. For example, border="blue" draws the border in the specified color, and border=1:3 can be used to draw borders of multiple boxplots using a vector of three colors.
col
fill color used for boxes. If col is not specified, boxcol will be used (see below). The col argument can be specified as a single color value or a vector of color values. For example, col="blue" fills the box with the specified color, and col=1:3 can be used to fill multiple boxes using a vector of three colors.
boxcol
filled box color(s). If one number is supplied, the box will be filled with the indicated color. If a vector of two non-negative numbers is supplied, the area below the median will be filled with the first color and the area above the median will be filled with the second color. A color of 0 can be used to designate filling with the background color. A specification of boxcol=-1 is used to designate "no fill" at all. The default is to fill with color 3, but the "att" and "old" styles set this for no filling.
medchar
logical flag indicating whether to show the median as a plotted character. This parameter is implicitly set to TRUE if a medpch parameter is supplied. The default is FALSE, but the "att" style implicitly sets the default to TRUE (by specifying medpch).
medpch
median plotting character. Setting this parameter implicitly sets the medchar parameter to be TRUE. The special value, NA, can be used to indicate the current plotting character ( par("pch")).The default is NA, but the "att" style set the default to 16 (filled octagon).
medline
logical flag indicating whether to show the median as a line across the box. This parameter is implicitly set to TRUE if the medlwd parameter is supplied. The default is TRUE, but the "att" style sets it to FALSE.
medlwd
median line width. Setting this parameter implicitly sets the medline parameter to TRUE. The special value, NA, is used to indicate the current line width ( par("lwd")). The default is 5, but the "old" and "att" styles set the it to 5.
medcol
the color of the median line or character. The special value, NA, indicates the current plotting color ( par("col")). The default is 0 (the background color), but the "old" and "att" styles set the default to NA.
confint
confidence interval logical flag. If TRUE, use z$conf to display confidence intervals. How the confidence intervals are shown is determined by the confnotch, confcol, confangle and confdensity parameters.
confnotch
confidence interval notch logical flag. If TRUE, confidence intervals will be notched. The default is FALSE, but the "old" and "att" styles set this parameter to TRUE.
confcol
confidence interval color. If supplied, confidence intervals will be filled with the indicated color. The default is 2, but the "old" and "att" styles set it to -1 (no filling).
confangle
confidence interval hatching angle. If supplied, confidence intervals will be hatched at the indicated angle, in degrees. If confdensity is supplied and confangle is not, confangle defaults to 45.
confdensity
confidence interval hatching density. If supplied, confidence intervals will hatched at the indicated density, in lines per inch. If confangle is supplied and confdensity is not, confdensity defaults to 25.
whisklty
whisker line type. The special value, NA, indicates the current line type ( par("lty")). The default is 2 (dotted line), but the "old" and "att" styles set it to 4 (dashed line).
staplelty
staple (whisker end cap) line type. The special value, NA, indicates the current line type ( par("lty")). The default is 1 (solid line), but the "att" style sets the default to 4 (dashed line).
staplewex
staple width expansion. Proportional to the box width. The default is 1, but the "old" style sets the default to 0.125.
staplehex
staple height expansion. Proportional to a standard height of about 1/100th the height of the plotting area. The default is 1 but the "old" style sets the default to 0.
outchar
logical flag indicating whether to show the outliers as a plotted characters. This parameter is implicitly set to TRUE if an outpch parameter is supplied. The default is FALSE, but the "old" style sets it to TRUE, and the "att" style implicitly sets it to TRUE (by setting outpch).
outpch
outlier plotting character. Setting this parameter implicitly sets the outchar parameter to be TRUE. The special value, NA, indicates the current plotting character ( par("pch")). The default is NA, but the "att" style sets the default to 1 (an octagon).
outline
logical flag indicating whether to show the outliers as horizontal lines. This parameter is implicitly set to TRUE if the outwex parameter is supplied. The default is TRUE, but the "old" and "att" styles set it to FALSE.
outwex
outlier line width expansion, proportional to the box width. The default is 1.

Graphical parameters may also be supplied as arguments to this function (see ). In addition, the high-level graphics arguments described under and the arguments to may be supplied to this function. However, bxp will always use linear axes: the log and [xy]axt arguments are ignored.

VALUE:

invisible vector which contains the x-coordinates of the centers of the boxes. This vector is useful for adding to the plot.

SIDE EFFECTS:

A plot is produced on the current graphics device.

Outlier lines and points are always drawn in color 1 of the palette.

DETAILS:

This function is called by boxplot.

SEE ALSO:

, , .

EXAMPLES:

# Save boxplot statistics by specifying "plot=F"
lottery.boxplot <- boxplot(split(lottery.payoff,
                      lottery.number%/%100), plot=F)
# Plot boxplots and save x-axis coordinates
lottery.bxp <- bxp(lottery.boxplot)
# Add counts to plot 
text(paste("n=", lottery.boxplot$n, sep=""),
     x=lottery.bxp, y=0.85*min(lottery.payoff))