R help - Nov 2005 - Greek letters in plots

Hi, all.  I know that this is probably something that others have asked,
but I can't find a reference in either the FAQ or the help pages.

 

I'm trying to find a way to put Greek letters as a label of the plot
*with* a value from the data.  Previously I've used pasted and the word
"rho".

 

*      paste("rho=", cor2[i])

 

will produce a label of "rho=0.74", or whatever.  But if I use
'substitute' or 'evaluate' commands in order to get a real Greek
letter,
I lose the ability to paste it with a data value.

 

Any ideas?

 

Thanks, Jo

 

Jo Hardin

Assistant Professor

Department of Mathematics

Pomona College

610 N. College Ave.

Claremont, CA 91711

909-607-8717

jo.hardin@pomona.edu

 



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Johanna Hardin wrote:
> 
> *      paste("rho=", cor2[i])
> will produce a label of "rho=0.74", or whatever.  But if I use
> 'substitute' or 'evaluate' commands in order to get a real
Greek letter,
> I lose the ability to paste it with a data value.
  Use parse() to turn that text into an expression. And use '==':

  > rho=0.78
  > plot(1:10,main=parse(text=paste("rho == ",rho)))

Not sure where your label is going, but the same thing should work for 
axes and text labels.

Baz

On Tue, 2005-11-01 at 05:20 -0800, Johanna Hardin wrote:
> Hi, all.  I know that this is probably something that others have asked,
> but I can't find a reference in either the FAQ or the help pages.
> 
> I'm trying to find a way to put Greek letters as a label of the plot
> *with* a value from the data.  Previously I've used pasted and the word
> "rho".
>
> *      paste("rho=", cor2[i])
> 
> will produce a label of "rho=0.74", or whatever.  But if I use
> 'substitute' or 'evaluate' commands in order to get a real
Greek letter,
> I lose the ability to paste it with a data value.
> Any ideas?
> Thanks, Jo
Try this:

  cor2 <- 0.74
  plot(1:5)
  title(bquote(rho == .(cor2)))

See ?plotmath and ?bquote for more information, noting the use of
the .(Variable) syntax for variable substitution.

HTH,

Marc Schwartz