[R] Paste symbol and calculation in plot

[Jonathan R. Blaufuss]

Scott,
  Thanks! That works great. I appreciate the help.

Jonathan

----- Original Message -----
From: "Scott Sherrill-Mix" <shescott at mail.med.upenn.edu>
To: "Jonathan R. Blaufuss" <blaufusj at carleton.edu>
Cc: r-help at r-project.org
Sent: Tuesday, August 11, 2009 4:18:18 PM GMT -06:00 US/Canada Central
Subject: Re: [R] Paste symbol and calculation in plot

I'm no expert at this but it seems like ?plotmath is saying to do
something like:

text(2,0.35,bquote(sigma==.(mySigma),list('mySigma'=round(sd(Data),digits=3))))


Scott



Scott Sherrill-Mix
Department of Microbiology
University of Pennsylvania
402B Johnson Pavilion
3610 Hamilton Walk
Philadelphia, PA  19104-6076



On Tue, Aug 11, 2009 at 4:00 PM, Jonathan R.
Blaufuss<blaufusj at carleton.edu> wrote:
> I'm trying to annotate a density plot and I would like to have R calculate the
> standard deviation and place it in the plot next to the standard deviation symbol
> "sigma". I can successfully use the text command to paste "StDev =",round(sd(Data),digits=3))
> on the plot. However, I have trouble when I want to replace "StDev" with the Greek
> symbol sigma (See code below).
>
>        set.seed(1)
>        Data=rnorm(100)
>        plot(density(Data))
>        text(2,0.35,paste("StDev =",round(sd(Data),digits=3)))
>
> Through searching the help files I figured out that I can paste the sigma symbol on the
> plot using the command "expression".
>
>        text(2,0.3,expression(paste(sigma," = 0.898")))
>
> However, when I try to paste together the sigma symbol and the standard deviation
> that R is calculating, the text of the command to calculate the standard deviation
> shows up on the plot instead of the number which I am asking it to calculate.
>
>        text(2.2,0.25,expression(paste(sigma," = ",round(sd(Data),digits=3))))
>
> Can someone please point me to a resource that will help me figure this out?
>
> Thank You,
>
> Jonathan
>
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