[R] xyplot auto.key issue

Mike Lawrence Mike.Lawrence at Dal.Ca
Sat Jul 30 21:04:37 CEST 2005

Hi all,

I'm having a problem with the auto.key function in xyplot. I hate to bother the
list like this and I'm positive I must be missing something very simple, yet
I've spent the last day searching for a solution to no avail.

Essentially, I want a key that contains entries in which the plot points are
superimposed on a line of the same color as the points, like this: o--o--o
Now, given the presence of the default "divide" command, I assume this is
simple; indeed, I get the impression that this representation is supposed to be
produced automatically. Yet I can't seem to get it to work!

Now, I've incorporated various other tweaks to my xyplot function, so I'm
wondering if these tweaks are somehow hindering my efforts. The function is
pasted below; I am making a 3x3 plot, each panel contains 5 lines and it is
these lines that I want represented in the key. See the comments for
descriptions of the modifications.

Any help would be greatly appreciated.



	#basic settings
	bias ~ sample_size | measure,
	data = bias,
	groups = exp_tau,
	type = "b",
	pch = c(1,2,3,4,5),
	#make strips transparent
	strip = function(bg, ...) strip.default(bg = 'transparent', ...),
	# tweak scales
			at = c(20, 40, 60),
			tck = c(1,0),
			alternating = F
			at = c(-50, -25, 0, 25, 50),
			tck = c(1,0),
			alternating = F
	# tell key to match symbols to those used in the plot
	par.settings = list(
		superpose.symbol = list(
			cex = .8,
			pch = c(1,2,3,4,5)
		lines = T,
		type = "b"
	# key settings
	auto.key = list (
		lines = T,
		size = 7,
		border = T,
		cex.title = 1.2,
		title = "Expected Tau",
		text = c("30 ms", "80 ms", "130 ms", "180 ms", "230 ms"),
		space = "right",


Mike Lawrence, BA(Hons)
Research Assistant to Dr. Gail Eskes
Dalhousie University & QEII Health Sciences Centre (Psychiatry)

Mike.Lawrence at Dal.Ca

"The road to Wisdom? Well, it's plain and simple to express:
Err and err and err again, but less and less and less."
- Piet Hein

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