# [R] puzzled with plotmath II

S Ellison S.Ellison at lgc.co.uk
Fri Jan 21 00:53:22 CET 2011

```expression(Z[i][i])

also works as expected, though without the comma.

S Ellison

>>> Gerrit Eichner <Gerrit.Eichner at math.uni-giessen.de> 01/20/11 12:09 PM >>>
Try

> plot (1, 1, ylab = expression (Z[list(i,i)]))

Hth  --  Gerrit

> -------- Original Message --------
> Subject: puzzled with plotmath
> Date: Thu, 20 Jan 2011 12:48:18 +0100
> From: Claudia Beleites <cbeleites at units.it>
> To: R Help <r-help at r-project.org>
>
> Dear all,
>
> I'm puzzled with matrix indices in plotmath.
>
> I'm plotting matrix elements: Z [i, i], and I'd like to put that as label.
> I'll
> describe what I want and what I get in LaTeX-notation.
>
> The output should look like Z_{i, i}, and my first try was
> plot (1, 1, ylab = expression (Z[i, i]))
>
> That, however, gives me Z_{i} (no comma, no second i) although the expression
> looks OK to me:
>> a <- expression (Z[i, i])
>> a [[1]]
> Z[i, i]
>> str (as.list (a [[1]]))
> List of 4
> \$ : symbol [
> \$ : symbol Z
> \$ : symbol i
> \$ : symbol i
>
> I'm able to tweak the ouput looking as I want:
> plot (1, 1, ylab = expression (Z[i][", "][i]))
> which is, however, logically very far from what I want to express.
>
> What am I missing?
>
> I'm almost sure this has been discussed before, but I can't find it: can
> anyone
> point me to good search terms? Is it possible to search for the terms being
> close to each other in RSiteSearch and/or RSeek? I get lots of introductory
> documents as they point to plotmath and discuss matrices...
>
> Thanks a lot for your help,
>
> Claudia
>
>> sessionInfo ()
> R version 2.12.1 (2010-12-16)
> Platform: x86_64-pc-linux-gnu (64-bit)
>
> locale:
> [1] LC_CTYPE=en_US.utf8       LC_NUMERIC=C              LC_TIME=en_US.utf8
> [4] LC_COLLATE=en_US.utf8     LC_MONETARY=C
> LC_MESSAGES=en_US.utf8
> [10] LC_TELEPHONE=C            LC_MEASUREMENT=en_US.utf8 LC_IDENTIFICATION=C
>
> attached base packages:
> [1] grid      stats     graphics  grDevices utils     datasets  methods
> base
>
> other attached packages:
> [1] ggplot2_0.8.8 proto_0.3-8   reshape_0.8.3 plyr_1.2.1
>
> loaded via a namespace (and not attached):
> [1] digest_0.4.2 tools_2.12.1
>
> --
> Claudia Beleites
> Dipartimento dei Materiali e delle Risorse Naturali
> Università degli Studi di Trieste
> Via Alfonso Valerio 6/a
> I-34127 Trieste
>
> phone: +39 0 40 5 58-37 68
> email: cbeleites at units.it
>
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