Hi
[shifting to r-devel]
On 13/09/2010 8:43 a.m., David Winsemius wrote:
On Sep 12, 2010, at 4:11 PM, Paul Murrell wrote:
Hi
On 13/09/2010 7:57 a.m., baptiste auguie wrote:
Oh, right I see. I was completely off then. Maybe it's not so easy to
add<> delimiters after all, I'll have to look at the list of symbol
pieces to see if these can be constructed too.
The plotmath stuff assumes a font with an Adobe Symbol encoding.
The characters we have to play with are shown at
http://www.stat.auckland.ac.nz/~paul/R/CM/AdobeSym.pdf
.
You can see the components of "growable" delimiters on the bottom
two rows.
Hello Paul;
Both Baptiste and I have looked at the plotmath.c code and it appears
that only a few of those delimiters are supported. We specifically
have tried to use the angle brackets:
> plot(1,1,
xlab=expression(bgroup(symbol(0xe1),atop(x,y),symbol(0xf1))))
Error in bgroup(symbol(225), atop(x, y), symbol(241)) :
invalid group delimiter
The supported delimiters appear to each be built up from three parts
that are then assembled within a bounding box and as far as I can
determine are limited to "|", "||", "[", "{", "(", ")", "}",and "}". I
needed to download the full source to find a copy, but I'm fairly sure
a guRu of your standing needs no help finding the code that handles
the bgroup display inside plotmath.c. I am not at my machine where I
was looking at it, but the code that I just found in expanded form on
the Internet bore your name as a copyright holder.
So I guess my feature request would be:
---add option for using scalable single character delimiters such as
Symbol(0xe1) and Symbol(0xe1).
Unfortunately, I don't think this is trivial. How are these supposed to
scale? Just get drawn bigger? (which is unlikely to produce nice
results because the lines will get thicker).
I'm guessing that the reason three-component delimiters were chosen is
that it was easier to expand the middle section while not expanding
the ends as much but that's just the guess of someone who is perusing
without really being able to fully grasp the intricacies of what is
being done.
That's about right. This is all modelled on TeX's equation formatting
algorithms. The Computer Modern fonts have this kind of extendable
components for very large delimiters, but for angled brackets it looks
like the TeX solution is just to offer various "big" versions. For
example, try the following TeX document ...
\documentclass{article}
\begin{document}
\[ \left\{
\begin{array}{ccc}
a & b & c \\
a & b & c \\
a & b & c \\
a & b & c \\
a & b & c \\
a & b & c \\
a & b & c \\
d & e & f \end{array}
\right\} \]
\[ \left\langle
\begin{array}{ccc}
a & b & c \\
a & b & c \\
a & b & c \\
a & b & c \\
a & b & c \\
a & b & c \\
a & b & c \\
d & e & f \end{array}
\right\rangle \]
\end{document}
Paul
--
Dr Paul Murrell
Department of Statistics
The University of Auckland
Private Bag 92019
Auckland
New Zealand
64 9 3737599 x85392
p...@stat.auckland.ac.nz
http://www.stat.auckland.ac.nz/~paul/
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