[R] lattice: how to "center" a subtitle?

[David Scott]

  On 05/04/11 13:14, David Winsemius wrote:
> On Apr 4, 2011, at 9:03 PM, David Winsemius wrote:
>
>> On Apr 4, 2011, at 8:42 PM, David Scott wrote:
>>
>>> On 05/04/11 05:58, David Winsemius wrote:
>>>> On Apr 4, 2011, at 1:27 PM, Marius Hofert wrote:
>>>>
>>>>> Dear David,
>>>>>
>>>>> do you know how to get plotmath-like symbols in both rows?
>>>>> I tried s.th. like:
>>>>>
>>>>> lab<- expression(paste(alpha==1, ", ", beta==2, sep=""))
>>>>> xlab<- substitute(expression( atop(lab==lab., bold(foo)) ),
>>>>> list(lab.=lab))
>>>>> xyplot(0 ~ 0, xlab = xlab)
>>>> I _did_ have plotmath functions in both rows: But here is your
>>>> solution:
>>>>
>>>> xyplot(0 ~ 0,  xlab =
>>>>      expression( atop(paste(alpha==1, "   ", beta==2), bold(bla) )) )
>>>>        )
>>>>
>>>> Note that `paste` in plotmath is different than `paste` in regular
>>>> R.
>>>> It has no `sep` argument. I did try both substitute and bquote on
>>>> you
>>>> externally expression,  but lattice seems to be doing some non-
>>>> standard evaluation and I never got it to "work". Using what I
>>>> thought
>>>> _should_ work, does work with `plot`:
>>>>
>>>>>   x=1;y=2
>>>>>   plot(0 ~ 0, xlab = bquote( atop(alpha==.(x)*","~beta==.(y),
>>>> bold(foo) ) )
>>>> + )
>>>>
>>>> But the same expression throws an error with xyplot:
>>>>>   x=1;y=2
>>>>>   xyplot(0 ~ 0, xlab = bquote( atop(alpha==.(x)*","~beta==.(y),
>>>> bold(foo) ) )
>>>> + )
>>>> Error in trellis.skeleton(formula = 0 ~ 0, cond = list(1L), aspect =
>>>> "fill",  :
>>>>    could not find function "atop"
>>> I am not sure where I read it and I can't find it again, but my
>>> understanding is that expressions using bquote with lattice need to
>>> be enclosed in as.expression() to work. That is in contrast to what
>>> happens in base graphics.
> Perhaps here:
> http://finzi.psych.upenn.edu/Rhelp10/2010-August/250832.html

I am pretty sure that was where I saw it. I knew it was out there somewhere.

> Or here:
> http://finzi.psych.upenn.edu/Rhelp10/2009-July/203714.html
>
> Although I disagree with Heimstra that reading the help(bquote)
> provides "more details" that might shed light on why this is so.
>

David Scott

-- 
_________________________________________________________________
David Scott	Department of Statistics
		The University of Auckland, PB 92019
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Director of Consulting, Department of Statistics