Yes, this does work as long as the data are spaced far enough apart. If you peek inside ./main/plot.c, you will find the function 'do_plot_xy' which provides the functionality I desire for standard graphics. A down-and-dirty implementation for lattice might be along the lines of
my.panel <- function(x, y, ...){ panel.xyplot(x, y, ...) d <- 0.5 # for now, should be half the size of 'cex' xold <- NA yold <- NA for(i in 1:length(x)){ xx <- x[i] yy <- y[i] f <- d / sqrt(xx * xx + yy * yy) if(f < 0.5){ # just a kludge for now, would really want to use grid.lines or some such panel.lines(x = c(xold + f * (xx - xold), xx + f * (xold - xx)), y = c(yold + f * (yy - yold), yy + f * (yold - yy))) } xold <- xx yold <- yy } } Unfortunately this is not quite right; to do it correctly it seems one has to address two problems: 1. how to get the size of the default 'cex' to use for 'd' (do_xy_plot uses 'GConvertYUnits' to accomplish this) 2. figure out how to achieve the same effect as what 'GConvert(&xx, &yy, USER, INCHES, dd)' does in do_xy_plot. Otherwise, the gap sizes are not constant. (1) sounds easy but I don't know the answer offhand. (2) seems more subtle. Any suggestions would be greatly appreciated. Ben Sundar Dorai-Raj wrote: >I think Paul's suggestion works if you use: > > panel.points(x, y, col = "white", cex = 1.5, pch = 16, ...) > >instead of the default background color. For me >trellis.par.get("background")$col returns "transparent". > >HTH, > >--sundar > > >
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