[R] Using sunflowerplot to add points in a xyplot panel

[Sundar Dorai-Raj]

Ronaldo Reis Junior said the following on 8/14/2007 7:08 AM:
> Hi,
> 
> I use panel.points to add points to a xyplot graphic. But I like to use the 
> sunflowerplot to plot my points because this is very superimposed. It is 
> possible to use this? I try but it dont work directly. It may be need to put 
> this function inside a panel.??? 
> 
> Thanks
> Ronaldo

You'll need to write your own panel function. Here's one shot at it. 
Most of the code is from ?sunflowerplot with added touches for lattice 
capability.

HTH,

--sundar

panel.sunflowerplot <- function(x, y, number, log = "", digits = 6, 
rotate = FALSE,
                                 cex.fact = 1.5, size = 1/8, seg.col = 
2, seg.lwd = 1.5, ...) {
   n <- length(x)
   if(missing(number)) {
     x <- signif(x, digits = digits)
     y <- signif(y, digits = digits)
     orderxy <- order(x, y)
     x <- x[orderxy]
     y <- y[orderxy]
     first <- c(TRUE, (x[-1] != x[-n]) | (y[-1] != y[-n]))
     x <- x[first]
     y <- y[first]
     number <- diff(c((1:n)[first], n + 1))
   } else {
     if(length(number) != n)
       stop("'number' must have same length as 'x' and 'y'")
     np <- number > 0
     x <- x[np]
     y <- y[np]
     number <- number[np]
   }
   n <- length(x)
   n.is1 <- number == 1
   cex <- trellis.par.get("plot.symbol")$cex
   if(any(n.is1))
     lpoints(x[n.is1], y[n.is1], cex = cex, ...)
   if(any(!n.is1)) {
     lpoints(x[!n.is1], y[!n.is1], cex = cex/cex.fact, ...)
     i.multi <- (1:n)[number > 1]
     ppin <- par("pin")
     pusr <- unlist(current.panel.limits())
     xr <- size * abs(pusr[2] - pusr[1])/ppin[1]
     yr <- size * abs(pusr[4] - pusr[3])/ppin[2]
     i.rep <- rep.int(i.multi, number[number > 1])
     z <- numeric()
     for (i in i.multi) z <- c(z, 1:number[i] + if (rotate) 
stats::runif(1) else 0)
     deg <- (2 * pi * z)/number[i.rep]
     lsegments(x[i.rep], y[i.rep], x[i.rep] + xr * sin(deg),
               y[i.rep] + yr * cos(deg), col = seg.col, lwd = seg.lwd)
   }
}

library(lattice)
xyplot(Petal.Width ~ Petal.Length, iris, panel = panel.sunflowerplot)