Common keys on separate lattice plots

Mon, Dec 2, 2002 6:57 PM #

In 'normal' plotting, by using text(.... outer = TRUE), I can set a
title that can refer to multiple plots.

I'm trying to achieve a similar effect with several trellis objects
with which I wish to use a common key.  I can only think of
complicated ways of achieving such an end by using a separate grid
graphic which didn't have any plot, but text only.

Is there something more elegant?

best

Patrick Connolly
HortResearch
Mt Albert
Auckland
New Zealand 
Ph: +64-9 815 4200 x 7188
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Deepayan Sarkar

Mon, Dec 2, 2002 8:55 PM #

On Monday 02 December 2002 07:56 pm, Patrick Connolly wrote:

I'm guessing that you are positioning your plots by calling print.trellis 
explicitly with the position/split argument. Once these are complete, the 
whole plotting region should be the default viewport, so you could simply use 
grid.text to write your title. for example,

foo <- xyplot(...)

print(foo, position = c(0,0,.5,.8), more = TRUE)
print(foo, position = c(.5,0,1,.8), more = FALSE)
grid.text("Title", x = .5, y = .9) 

If by key you mean a legend (as produced by 'key' in a lattice call), you 
could use something like

draw.key(key = list(rect = list(col = 1:3)), 
         draw = TRUE, 
         vp = viewport(x=.5, y=.9))  

In either case, you would have to position the initial plots so that enough 
space is left.

Hope that helps.

-Deepayan