[R] Names of Greek letters stored as character strings; plotmath.

[Bert Gunter]

..and a final addendum:

xnm <- quote(gamma)
## makes xnm the name gamma not the string "gamma"

plot(0,xlab = bquote( .(xnm))

-- Bert

On Sat, May 19, 2012 at 7:23 AM, Bert Gunter <bgunter at gene.com> wrote:
> ... and here is another incantation that may be  informative.
>
> xnm<- as.name("gamma')  ## This does the parsing
> plot(0, xlab =bquote(.(xnm))
>
> The initial puzzle is that if you just set
> xnm <- "gamma"
>
> bquote will insert the string "gamma" rather than the symbol. After
> all, that's what plotmath sees for xnm. So the key is telling plotmath
> that it's a symbol, not a string. This can either be done before, as
> above, or inline, as you and Gabor showed. Unsurprisingly. this also
> does it, since as.name() is doing the parsing:
>
> xnm <- "gamma"
>  plot(0,xlab=bquote(.(as.name(xnm))))
>
> AND we are adhering to Thomas's dictum: bquote is a wrapper for
> substitute(), which is what he recommends as the preferable
> alternative to eval(parse(...)) . But, heck -- all such software
> principles are just guidelines. Whatever works (robustly).
>
> HTH.
>
> Cheers,
> Bert
>
> On Sat, May 19, 2012 at 3:17 AM, Gabor Grothendieck
> <ggrothendieck at gmail.com> wrote:
>> On Sat, May 19, 2012 at 1:18 AM, Rolf Turner <rolf.turner at xtra.co.nz> wrote:
>>>
>>> I had such good luck with my previous question to r-help, (a few minutes
>>> ago) that I thought I would try again with the following query:
>>>
>>>> Suppose I have
>>>>
>>>>    xNm <- "gamma"
>>>>
>>>> I would like to be able to do
>>>>
>>>>    plot(1:10,xlab = <something involving xNm">)
>>>>
>>>> and get the x axis label to be the Greek letter gamma
>>>> (rather than the literal text string "gamma").
>>>>
>>>> Is this possible?  I've messed around with substitute()
>>>> and bquote() and got nowhere.
>>>
>>>
>>> Then, just before clicking on "Send", I had one more thimk, and blow
>>> me down, I got something that worked:
>>>
>>> plot(1:10,xlab=eval(expression(parse(text=xNm))))
>>>
>>
>> That can be shortened to:
>>
>> plot(0, xlab = parse(text = xNm))
>>
>> --
>> Statistics & Software Consulting
>> GKX Group, GKX Associates Inc.
>> tel: 1-877-GKX-GROUP
>> email: ggrothendieck at gmail.com
>>
>> ______________________________________________
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>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>
>
>
> --
>
> Bert Gunter
> Genentech Nonclinical Biostatistics
>
> Internal Contact Info:
> Phone: 467-7374
> Website:
> http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm



-- 

Bert Gunter
Genentech Nonclinical Biostatistics

Internal Contact Info:
Phone: 467-7374
Website:
http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm