Plotrix R package polar.plot symbol overwrite

Question

I'm using a polar plot to describe satellite position during a time series. The following question uses the polar.plot function from the R package plotrix. An example plot:

library(plotrix)
polar.plot(c(0,1,3,4),c(30,60,90,120),start=90,clockwise=TRUE,rp.type="s",
                          point.symbols=19,radial.lim=c(0,5),boxed.radial=F)

The issues I'm running across is that this function plots the labels and axis over the data values (see radial positions 0 and 3), and I don't see a way to control this behavior. I can run a workaround by adding the data values again (adding to the previous plot) with axis and labels turned off, but this is less than elegant:

polar.plot(c(0,1,3,4),c(30,60,90,120),start=90,clockwise=TRUE,rp.type="s",
           grid.left=F,point.symbols=19,show.radial.grid=FALSE,
           show.grid.labels=FALSE,show.grid=FALSE,labels=NULL,add=TRUE)

My question is two fold:

1. Is there a way to control this in plotrix that I've missed in the documentation?
2. Is there another package that can easily handle this kind of azimuth polar plot?

Answer 1

You can control the way those radial labels are displayed with two parameters: show.grid.labels and radial.labels. See ?radial.plot for more complete information.

show.grid.labels accepts values from 1 to 4 (similar to that of pos or axis, see ?par or ?axis) controlling the side on which they are displayed. radial.labels accepts a vector of labels, so if you want the labels to be turned down: radial.labels = "" works,

library(plotrix)
polar.plot(c(0,1,3,4),c(30,60,90,120),start=90,clockwise=TRUE,rp.type="s",
           point.symbols=19,radial.lim=c(0,5),boxed.radial=FALSE, 
           show.grid.labels=2)

polar.plot(c(0,1,3,4),c(30,60,90,120),start=90,clockwise=TRUE,rp.type="s",
           point.symbols=19,radial.lim=c(0,5),boxed.radial=FALSE, 
           show.grid.labels=2, radial.labels=c("",1:5))

You can also get rid of the axial lines using show.radial.grid:

polar.plot(c(0,1,3,4),c(30,60,90,120),start=90,clockwise=TRUE,rp.type="s",
           point.symbols=19,radial.lim=c(0,5),boxed.radial=FALSE, 
           show.grid.labels=2, radial.labels=c("",1:5), 
           show.radial.grid=FALSE)

However there doesn't seem to be a way of making the lines lie behind the labels and the points, so if you do want the lines to appear behind then your original idea was probably the best:

polar.plot(NA,NA,start=90,clockwise=TRUE,rp.type="",
           radial.lim=c(0,5),boxed.radial=FALSE, show.grid.labels=2,
           radial.labels=c("",1:5)) # First plotting the grid
polar.plot(c(0,1,3,4),c(30,60,90,120),start=90,clockwise=TRUE,rp.type="s",
           point.symbols=19,radial.lim=c(0,5),show.grid=FALSE, 
           show.radial.grid=FALSE, add=TRUE)  # Then the points without the grid

I don't know of any other package having a function handling this kind of plot, however if you want to create your own function, this answer to your previous question can definitely help you start.