>>>>> "PE" == Peter Ehlers <ehl...@ucalgary.ca>
>>>>> on Fri, 21 Jan 2011 06:17:20 -0800 writes:
PE> On 2011-01-21 02:27, Martin Maechler wrote:
>> Thank you, Claudia,
>>
>>>>>>> "CB" == Claudia Beleites<cbelei...@units.it> on Thu,
>>>>>>> 20 Jan 2011 14:05:41 +0100 writes:
>>
CB> Dear all, I just stumbled over the fact that subsetting
CB> by square bracket will only output the first given
CB> index. I guess the rest is thrown away by the CADDR in
CB> RenderSub (plotmath.c l. 1399). Maybe changing this
CB> could be considered as "low-priority desired" (would be
CB> nice if the output works for ?
>>
>> I agree this is a ``missing feature'' and well worth wish
>> list item.
>>
CB> However, I suggest to announce the fact that only the
CB> first parameter is printed in plotmath.Rd.
>>
CB> E.g. in the table l. 72 \code{x[i]} \tab x subscript i;
CB> escape further indices (\code{x ["i, j"]})\cr
>>
>> How would get the equivalent of LaTeX x_{i_1, j_2} ? Not
>> by making it a string (that's not escape, I'd say), but
>> by something like
>>
>> plot(0, axes=FALSE, main=
>> expression(paste(x[i[1]],{}[j[2]])))
>>
>> which works +- but of course is unnecessarily ugly,
>> compared to the desired
>>
>> plot(0, axes=FALSE, main= expression( x[i[1], j[2]]))
>>
PE> I don't know if I've ever disagreed with Martin's advice but,
:-)
PE> unless I'm missing something, Claudia wants something
PE> done about the second index in x[i, j] while Martin is
PE> talking about the case of cascading subscripts in
PE> 'x_sub_i_sub_1' (as shown in his LaTeX expression).
Well, that was a misunderstanding.
I've use "cascaded" subscripts as an example of subscripts that
are themselves expressions, and so using a string,
as Claudia's suggestion (on R-devel!) was, is not enough.
Only afterwards, I saw the related thread on R-help,
which included the proposals you give here
PE> Both situations are nicely handled with the 'list()' and '[]'
PE> constructs in plotmath:
PE> plot(0, axes=FALSE, main= expression( x[ list( i[1], j[2] ) ] ) )
PE> To handle Claudia's wish, it might be desirable to have plotmath.c
PE> automatically recognize such cases but I would consider that to
PE> be (as Claudia says) in the 'nice if' category. Claudia's suggestion
PE> for the help page could be handled by adding another example. Then
PE> again, plotmath (not surprisingly) is like LaTeX in that, the more
PE> you use it, the more you become familiar with the special constructs
PE> needed to get the output you want. I still find myself scurrying to
PE> ?plotmath and scanning the Syntax/Meaning table quite frequently.
okay.
Indeed, the following code snippet shows what I deem a summary
of the proposals seen.
Txt <- function(y, exp) {
y <- y/16 # to allow integer arguments on input
x0 <- par("xaxp")[1]
text(y, exp, adj = 0, cex = 5)
text(y, deparse(substitute(exp)), adj = 1.1, cex=1.2)
}
plot(0, axes=FALSE,ann=FALSE, asp=1, type="n")
## These show no "," between the two indices:
Txt( 0, expression(x[paste(i[1],j[2])]))
Txt( 2, expression(x[i[1]][j[2]])) ## <-- clearly nicest
## This one does .. that's what Claudia wanted:
Txt(-3, expression(x[list(i[1],j[2])]))
## and this one uses extra space
Txt(-5, expression(x[list(~i[1],j[2])]))
g <- seq(-1.6,1, .2)/4; abline(v=g+1, h=g, col=adjustcolor(1, .2))
Notably the distinction between (LaTeX)
x_{i,j} or x_{i_1, j_2}
and
x_{ij} or x_{i_1 i_2}
is something that the useR will want to be able to specify with
plotmath as well.
So Claudia's (and my) wish that x[i,j] (or x[i[1], j[2]] )
also work automatically in R's plotmath
would still have to say if we want the version with "," or
without.
Martin
PE> Peter Ehlers
>> Martin
>>
CB> Claudia
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
