[R] Changing the origin in polar.plot in plotrix package

[John Beamer]

Thanks Jim.

That works well, thanks. Is there a way I can specify the range as it
seems to adjust automatically. Also I was hoping to plot multiple
datasets on the same chart but with different colours.

In the normal plot() I can do this with col =  .... I was hoping to do
the same with points.col but it doesn't seem to work.

Thanks a lot for your help
John

On 16/12/2007, Jim Lemon <jim at bitwrit.com.au> wrote:
> 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
>