[R] Greek characters in plots

[michael watson (IAH-C)]

OK, I am definitely struggling here.

The text I am trying to plot isn't a mathematical expression, it's:

A) ΔstbA::cat 

This is biological notation for a particular mutation.  The "A)" part is a tag identifying the graph, and the "stbA::cat" bit is the gene that is mutated.  Both the tag and gene are set as variables in a loop, and only the delta remains the same.

As the text I am trying to plot isn't a mathematical expression, I seem to be having trouble getting substitute() and expression() to do what I want.  As plotmath states "A mathematical expression must obey the normal rules of syntax for any R expression", I fear I may be barking up the wrong tree!

Thank you all for your help so far, but can someone please help me once more and tell me how I can get the capital Delta symbol so I can use it in non-mathematical text and strings for plotting?

Thanks once again

Mick  

-----Original Message-----
From: Prof Brian Ripley [mailto:ripley at stats.ox.ac.uk] 
Sent: 05 August 2008 12:40
To: michael watson (IAH-C)
Cc: Henrique Dallazuanna; r-help at r-project.org
Subject: Re: [R] Greek characters in plots

On Tue, 5 Aug 2008, michael watson (IAH-C) wrote:

> Excellent!  I even tried DELTA but not Delta....

?plotmath says

       'Alpha' - 'Omega'               uppercase Greek symbols

How could that be made clearer?

(Note it carefully says Greek *symbols* not *character*: they are not the
same thing.)

> Now, how do I go about pasting that with some text that I have in various other variables?

Use substitute?  E.g.

substitute(expression(foo*Delta), list(foo=3))

(Some people prefer bquote, but that is just a wrapper for substitute in 
R.)

>
> -----Original Message-----
> From: Henrique Dallazuanna [mailto:wwwhsd at gmail.com]
> Sent: 05 August 2008 12:17
> To: michael watson (IAH-C)
> Cc: r-help at r-project.org
> Subject: Re: [R] Greek characters in plots
>
> Try,
>
> expression(Delta)
>
> On Tue, Aug 5, 2008 at 8:14 AM, michael watson (IAH-C)
> <michael.watson at bbsrc.ac.uk> wrote:
>> Hi
>>
>> I am running an R script that creates 100s of graphs, and I need to use
>> the greek CAPITAL letter delta in the mtext() function.
>>
>> I got as far as expression(delta) but this gives me the lowercase
>> version.
>>
>> Can anyone help?  I'm using R 2.7 on Windows XP
>>
>> Mick
>>
>> Head of Informatics
>> Institute for Animal Health
>> Compton
>> Berks
>> RG20 7NN
>> 01635 578411
>>
>> http://www.iah.ac.uk/research/bioinformatics/bioinf.shtml
>>
>> The information contained in this message may be confide...{{dropped:14}}
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
> -- 
> Henrique Dallazuanna
> Curitiba-Paraná-Brasil
> 25° 25' 40" S 49° 16' 22" O
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
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