John Beamer wrote:
> I am trying to draw a polar plot, which is easy enough to do in the
> plotrix package through the polar.plot function.
>
> However I would like to change the origin of the length vector. For
> instance all my length values are between 75 and 85, so instead of
> having the origin as 0 (the default) I'd like it to be, say, 50.
>
> Is there any way do to this in the polar.plot function, or if not is
> there an additional package that will accomplish this.
>
> I am running R 2.5 and the latest version of plotrix.
>
Hi John,
The short answer is no.
The long answer is:
radial.plot<-function(lengths,radial.pos=NULL,
labels=NA,label.pos=NULL,start=0,clockwise=FALSE,
rp.type="r",label.prop=1.1,main="",xlab="",ylab="",
line.col=par("fg"),mar=c(2,2,3,2),show.grid=TRUE,
show.radial.grid=TRUE,grid.col="gray",
grid.bg="transparent",grid.left=FALSE,
point.symbols=NULL,point.col=NULL,
show.centroid=FALSE,radial.lim=NULL,...) {
if(is.null(radial.lim)) radial.lim<-range(lengths)
length.dim<-dim(lengths)
if(is.null(length.dim)) {
npoints<-length(lengths)
nsets<-1
lengths<-matrix(lengths,nrow=1)
}
else {
npoints<-length.dim[2]
nsets<-length.dim[1]
lengths<-as.matrix(lengths)
}
lengths<-lengths-radial.lim[1]
lengths[lengths<0]<-NA
if(is.null(radial.pos))
radial.pos<-seq(0,pi*(2-2/npoints),length=npoints)
radial.pos.dim<-dim(radial.pos)
if(is.null(radial.pos.dim))
radial.pos<-matrix(rep(radial.pos,nsets),
nrow=nsets,byrow=TRUE)
else radial.pos<-as.matrix(radial.pos)
if(clockwise) radial.pos<--radial.pos
if(start) radial.pos<-radial.pos+start
if(show.grid) {
grid.pos<-pretty(radial.lim)
if(grid.pos[1] <= radial.lim[1])
grid.pos<-grid.pos[-1]
maxlength<-max(grid.pos-radial.lim[1])
angles<-seq(0,1.96*pi,by=0.04*pi)
}
else {
grid.pos<-NA
maxlength<-diff(radial.lim)
}
oldpar<-par("xpd","mar","pty")
par(mar=mar,pty="s")
plot(c(-maxlength,maxlength),c(-maxlength,maxlength),
type="n",axes=FALSE,
main=main,xlab=xlab,ylab=ylab)
par(xpd=TRUE)
if(length(line.col) < nsets) line.col<-1:nsets
rp.type<-unlist(strsplit(rp.type,""))
if(match("s",rp.type,0)) {
if(is.null(point.symbols)) point.symbols<-1:nsets
if(length(point.symbols)<nsets)
point.symbols<-rep(point.symbols,length.out=nsets)
if(is.null(point.col)) point.col<-1:nsets
if(length(point.col)<nsets)
point.col<-rep(point.col,length.out=nsets)
}
# split up rp.type if there is a combination of displays
for(i in 1:nsets) {
# get the vector of x positions
xpos<-cos(radial.pos[i,])*lengths[i,]
# get the vector of y positions
ypos<-sin(radial.pos[i,])*lengths[i,]
# plot radial lines if rp.type == "r"
if(match("r",rp.type,0))
segments(0,0,xpos,ypos,col=line.col[i],...)
if(match("p",rp.type,0))
polygon(xpos,ypos,border=line.col[i],col=NA,...)
if(match("s",rp.type,0))
points(xpos,ypos,pch=point.symbols[i],
col=point.col[i],...)
if(show.centroid)
points(mean(xpos),mean(ypos),col=point.col[i],
pch=point.symbols[i],cex=2,...)
}
if(missing(labels)) {
label.pos<-seq(0,1.8*pi,length=9)
labels<-as.character(round(label.pos,2))
}
if(clockwise) label.pos<--label.pos
if(start) label.pos<-label.pos+start
xpos<-cos(label.pos)*maxlength
ypos<-sin(label.pos)*maxlength
if(show.radial.grid) segments(0,0,xpos,ypos,col=grid.col)
xpos<-cos(label.pos)*maxlength*label.prop
ypos<-sin(label.pos)*maxlength*label.prop
boxed.labels(xpos,ypos,labels,ypad=0.7,border=FALSE)
if(show.grid) {
print(grid.pos)
for(i in seq(length(grid.pos),1,by=-1)) {
xpos<-cos(angles)*(grid.pos[i]-radial.lim[1])
ypos<-sin(angles)*(grid.pos[i]-radial.lim[1])
polygon(xpos,ypos,border=grid.col,col=grid.bg)
}
ypos<-rep(-maxlength/15,length(grid.pos))
boxed.labels(grid.pos-radial.lim[1],ypos,
as.character(grid.pos),border=FALSE)
}
par(oldpar)
}
But you will have to test it, and I would appreciate knowing if anything
breaks. Thanks.
Jim
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