legendg: Legend with grouped bars, lines or symbols

Description

Displays a legend with more than one rectangle, symbol or line.

Usage

legendg(x,y=NULL,legend,fill=NULL,col=par("col"),           border=list("black"),lty,lwd,pch=NULL,angle=45,density=NULL,        bty="o",bg=par("bg"),box.lwd=par("lwd"),box.lty=par("lty"),  box.col=par("fg"),pt.bg=NA,cex=1,pt.cex=cex,pt.lwd=lwd,   pt.space=1,xjust=0,yjust=1,x.intersp=1,y.intersp=1, adj=c(0,0.5),text.width=NULL,text.col=par("col"),merge=FALSE, trace=FALSE,plot=TRUE,ncol=1,horiz=FALSE,title=NULL, inset=0,xpd,title.col=text.col)

Arguments

x,y

Position of the legend as in legend.

legend

Labels for the legend as in legend.

fill

List of fill colors for the rectangles.

col

Color(s), perhaps as a list, for the symbols.

border

Border color(s) for the rectangles.

lty

Line type, currently ignored and set to 1.

lwd

Line width, currently ignored.

pch

List of symbols for the legend.

angle,density

Currently ignored.

bty

Legend box type to be displayed.

Background color for the legend.

box.lwd,box.lty,box.col

Line width, type and color for the surrounding box.

cex

Character expansion for text.

pt.bg,pt.cex,pt.lwd

Background color, character expansion and line width for the symbols.

pt.space

Spacing for the symbols as a multiplier for strwidth("O").

xjust,yjust

Justification for the legend.

x.intersp,y.intersp

x and y character spacing for the legend text.

adj

Text adjustment.

text.width,text.col

Width and color of the legend text.

merge

Whether to merge points and lines.

trace

Show how the legend is calculated.

plot

Whether to plot the legend.

ncol

Number of columns in the legend.

horiz

Whether to display a horizontal legend.

title

Title for the legend.

inset

Inset distances for use with keywords.

xpd

An optional value for par(xpd=).

title.col

Color for the legend title.

Value

The value returned by legend returned invisibly.

Details

legendg calls legend to display a legend with a blank space to the left of the labels. It then attempts to display groups of colored rectangles or symbols in that space depending upon the contents of either fill or pch. These should be in the form of a list with the number of elements equal to the number of labels, and one or more fills or symbols for each label. legendg will display up to four fills or symbols next to each label, allowing the user to label a group of these rather than just one per label.

Examples

Run this code

 plot(0.5,0.5,xlim=c(0,1),ylim=c(0,1),type="n",
  main="Test of grouped legend function")
 legendg(0.5,0.8,c("one","two","three"),pch=list(1,2:3,4:6),
  col=list(1,2:3,4:6),pt.space=1.5)
 legendg(0.5,0.5,c("one","two","three"),fill=list(1,2:3,4:6))
 # fake a line/point with text points
 legendg(0.2,0.25,c("letter","number"),
  pch=list(c("-","A","-"),c("-","1","-")),
  col=list(rep(2,3),rep(3,3)))