R help - Apr 2013 - Superscript

Hi,
How do I write a superscript within gsub?

I have the following: gsub("_mgkg",expression(paste("mg
kg"^{-1})),names[1])

Thanks



-- 
Shane

	[[alternative HTML version deleted]]

On 03/04/2013 11:01 AM, Shane Carey wrote:
> Hi,
> How do I write a superscript within gsub?
>
> I have the following: gsub("_mgkg",expression(paste("mg
kg"^{-1})),names[1])
>
gsub() doesn't work with expressions, it works with character strings.  
You're going to need to split your string into parts before and after 
the "_mgkg" string, and then put it together again as an expression.

Duncan Murdoch

gsub searches strings, not expressions.
---------------------------------------------------------------------------
Jeff Newmiller                        The     .....       .....  Go Live...
DCN:<jdnewmil at dcn.davis.ca.us>        Basics: ##.#.       ##.#.  Live
Go...
                                      Live:   OO#.. Dead: OO#..  Playing
Research Engineer (Solar/Batteries            O.O#.       #.O#.  with
/Software/Embedded Controllers)               .OO#.       .OO#.  rocks...1k
--------------------------------------------------------------------------- 
Sent from my phone. Please excuse my brevity.

Shane Carey <careyshan at gmail.com> wrote:
>Hi,
>How do I write a superscript within gsub?
>
>I have the following: gsub("_mgkg",expression(paste("mg
>kg"^{-1})),names[1])
>
>Thanks

Are you trying to convert a column name like "Na_mgkg" to a plot label
like Na (mg kg^-1) ?
If so you will have to use both string manipulation functions like gsub() and
expression manipulating
functions like bquote().  E.g.,

f <- function (name) 
{
   # add other suffices and their corresponding plotmath expressions to the list
   env <- list2env(list(mgkg = bquote(mg ~ kg^{-1}),
                        ugkg = bquote(mu * g ~ kg^{-1})),
                   parent = emptyenv())
   pattern <- paste0("_(", paste(objects(env),
collapse="|"), ")")
   bquoteExpr <- parse(text=gsub(pattern,
                                 "~(.(\\1))",
                                 name))[[1]]
   # I use do.call() to work around the fact that bquote's first argument is
not evaluated.
   do.call(bquote, list(bquoteExpr, env))
}

d <- data.frame("Na_mgkg"=1:10, "K_ugkg"=10:1)
plot(Na_mgkg ~ K_ugkg, data=d, xlab=f("K_ugkg"),
ylab=f("Na_mgkg"))

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org] On Behalf
> Of Shane Carey
> Sent: Wednesday, April 03, 2013 8:02 AM
> To: r-help at r-project.org
> Subject: [R] Superscript
> 
> Hi,
> How do I write a superscript within gsub?
> 
> I have the following: gsub("_mgkg",expression(paste("mg
kg"^{-1})),names[1])
> 
> Thanks
> 
> 
> 
> --
> Shane
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> 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.