将水平图例跨多行。

strwrap

lipsum <- \"Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur ullamcorper tellus vitae libero placerat aliquet egestas tortor semper. Maecenas pellentesque euismod tristique. Donec semper interdum magna, commodo vehicula ante hendrerit vitae. Maecenas at diam sollicitudin magna mollis lobortis. In nibh elit, tincidunt eu lobortis ac, molestie a felis. Proin turpis leo, iaculis non commodo quis, venenatis at justo. Duis in magna vel erat fringilla gravida quis non nisl. Nunc lacus magna, varius eu luctus vel, luctus tristique sapien. Suspendisse mi dolor, vestibulum at facilisis elementum, lacinia vitae metus. Etiam ut nisl urna, vel tempus mi. In hac habitasse platea dictumst. Quisque pretium volutpat felis, nec tempor diam faucibus at. Praesent volutpat posuere sapien, eu vulputate risus molestie vitae. Proin iaculis quam non leo porttitor hendrerit.\"

strwrap(lipsum)
cat(strwrap(lipsum), sep = \"\\n\")
# Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur ullamcorper tellus
# vitae libero placerat aliquet egestas tortor semper. Maecenas pellentesque euismod
# tristique. Donec semper interdum magna, commodo vehicula ante hendrerit vitae. Maecenas
# at diam sollicitudin magna mollis lobortis. In nibh elit, tincidunt eu lobortis ac,
# molestie a felis. Proin turpis leo, iaculis non commodo quis, venenatis at justo. Duis
# in magna vel erat fringilla gravida quis non nisl. Nunc lacus magna, varius eu luctus
# vel, luctus tristique sapien. Suspendisse mi dolor, vestibulum at facilisis elementum,
# lacinia vitae metus. Etiam ut nisl urna, vel tempus mi. In hac habitasse platea
# dictumst. Quisque pretium volutpat felis, nec tempor diam faucibus at. Praesent
# volutpat posuere sapien, eu vulputate risus molestie vitae. Proin iaculis quam non leo
# porttitor hendrerit.

# splits title of plot if to long
splittitle=function(title,linelength=40)
{
    spltitle<-strsplit(title,\' \')
    splt<-as.data.frame(spltitle)
    title2<-NULL
    title3<-NULL
    titlelength<-round(nchar(title)/round(nchar(title)/linelength))
    dimsplt<-dim(splt)
    n=1
    doonce2=0
    for(m in 1:round(nchar(title)/linelength)){
  doonce=0
    doonce2=0
    for(l in n:dimsplt[1]){
        if(doonce==0){title2<-title3}
        title2=paste(title2,splt[l,],sep=\' \')
        if(doonce2==0){if(nchar(title2)>=(titlelength*m)){title3=paste(title2,\'\\n\',sep=\'\')
        n<-(l+1)
        doonce2=1}
        }
        doonce=1
    }
    }
    title2
}

lab <- \"A really really long string!A really really long string!A really really long string!A really really long string!A really really long string!A really really long string!A really really long string!A really really long string!\"
lab2<-splittitle(lab)
cat(lab)
cat(lab2)


library(\'ggplot2\')

dat <- data.frame(grp = paste(1:6,lab2),x=1:6,y=runif(6))

ggplot(dat,aes(x=x,y=y,colour=grp)) + geom_point() + 
    opts(legend.position=\"bottom\",legend.direction=\"horizontal\")

dat <- data.frame(grp = paste(1:6,lab2),x=1:6,y=runif(6))
ggplot(dat,aes(x=x,y=y,colour=grp)) + geom_point() + 
    opts(legend.position=\"bottom\",legend.direction=\"horizontal\")

> splittitle(\"abc defg hi jkl m\", 6)

[1] \" abc defg\\n hi\\n jkl m\"

RGraphics::splitString

library(RGraphics)
multiLines <- function(text, maxWidth=11) {
  textLen = nchar(text)
  maxHeight = ceiling(textLen/maxWidth)*1.5
  vp=viewport(width=maxWidth,height=maxHeight, default.units=\"char\")
  pushViewport(vp) #activate the viewport
  text2 = splitString(text) #given vp, split the text
  popViewport() #get rid of it
  return(text2)
}