R help - Sep 2004 - bubble plots

Dear all,

I'm used to draw bubble plots (gstat) to get a first view of my spatial
marked data, but I can't find a way to label legend with marks after having
replaced them by a numeric scale.

I have a data frame with numeric coords and factors:
> names(data)
[1] "x"         "y"         "bloc"     
"sub"       "inoc"      "etat"
etc...
> levels(data$etat)
[1] ""    "F"   "Fi"  "NF" 
"NFi"


I do:
> levels(data$etat) <- c(0, 2, -2, 1, -1)
> data$etat <- as.numeric(as.vector(data$etat))
> C1 <- subset(data, sub=="C" & bloc=="1",
select=c(x, y, etat))
> x11()
> lset(theme = col.whitebg())
> bubble(C1, xcol = 1, ycol = 2, zcol = 3,
	xlab = "", ylab = "", main = "Bloc 1  -  Substrat
C",
	key.entries = min(C1[, 3]):max(C1[, 3]), maxsize=3)

I then obtain "-2", "-1", "O", etc. as legend
labels and cannot find
argument making it possible to label my legend with initial marks:
"F1",
NFi", etc.

Besides, I also tried with image() but I faced the following error message,
even though I ordered x- and y-coords:

Error in image.default(C1$x, C1$y, C1$etat) :
       increasing x and y values expected

I'd really appreciate if someone could give me either an option to label
adequately bubble plots, or even to make me know if there is another - maybe
better - way to plot spatial marked data.


Jacques VESLOT
CIRAD R??union

Jacques, please try the following:

 > z=factor(c('a', 'b','c'))
 > z
[1] a b c
Levels: a b c
 > x = c(1,2,3)
 > y = c(3,2,1)
 > xyplot(y~x,groups=z,auto.key=T,asp=diff(range(y))/diff(range(x)))

the asp argument takes care of one unit in x being equal to one unit in y.
If you add e.g. pch=z to vary symbols, auto.key will have to be replaced
by the more complex key argument, see ?xyplot

Color and symbol type are better to distinguish factor variables than
size is, so I'd recommend using xyplot rather than bubble (which uses
xyplot to plot bubbles)
--
Edzer