Wrapping / bending a text around a circle in plot (R)

Question

Is there any chance to write text which is \"wrapped\" around the circle? I mean something like this:

Answer 1

Yes, and here is the code, free of charge :-) . I wrote this a while back but I don't think ever published it in any CRAN package.

# Plot symbols oriented to local slope.
# Interesting problem: if underlying plot has some arbitrary aspect ratio,
# retrieve by doing: Josh O'B via SO:  
# myasp <- with(par(),(pin[2]/pin[1])/(diff(usr[3:4])/diff(usr[1:2])))
# so make that the default value of argument 'asp'
# Default is 'plotx' is vector of indices at which to 
# plot symbols.  If is_indices=FALSE, only then turn to splinefun to 
# calculate y-values and slopes; and user beware.
#
# 6 Feb 2014: added default col arg so can stick in a color vector if desired
# TODO
#
slopetext<-function(x,y,plotx, mytext, is_indices=TRUE, asp=with(par(), (pin[1]/pin[2])*(diff(usr[3:4])/diff(usr[1:2]))),offsetit= 0, col='black', ...) {
if (length(x) != length(y)) stop('data length mismatch')
if (!is.numeric(c(x,y,plotx) ) ) stop('data not numeric')
if(is_indices) {
    # plotting at existing points.
    if(any(plotx<=1) | any(plotx>= length(x))) {
        warning("can't plot endpoint; will remove")
        plotx<-plotx[(plotx>1 & plotx x[highs] )
    intcpts <- y[highs]-slopes*x[highs]   
    ploty <- intcpts + x[plotx]*slopes
    # change name, so to speak, to simplify common plotting code
    plotx<-x[plotx]
    }else{
    #interpolating at plotx values
        if  (any(plotxmax(x)) ) {
            warning("can't plot extrapolated point; will remove")
            plotx<-plotx[(plotx>min(x) & plotx

Edit: per David's excellent suggestion, a sample case:

x <- 1:100
y <- x/20 + sin(x/10)
plot(x,y,t='l')
slopetext(x=x,y=y,plotx=seq(10,70,by=10),mytext=letters[1:8])

The third argument in this example selects every tenth value of (x,y) for placement of the text. I should warn that I haven't idiot-proofed the is_indices=FALSE case and the spline fit may in extreme cases place your text in funny ways.