[R] Dealing with parentheses within variable names

[Duncan Murdoch]

On 01/03/2013 11:20 AM, William Dunlap wrote:
> > R shouldn't have trouble with names like that
>
> You will need to enclose the names with backquotes, `odd Name (parens)`, when using them
> in expressions.  E.g.,
>
>    > d <- data.frame(`P/E`=c(20,25,22), `% Growth`=c(2.4, 2.8, 5.0), `+-`=c(TRUE,TRUE,FALSE), check.names=FALSE)
>    > # In the former you could use "P/E"=, but `P/E` works.  check.names=FALSE stops name mangling
>    > d
>      P/E % Growth    +-
>    1  20      2.4  TRUE
>    2  25      2.8  TRUE
>    3  22      5.0 FALSE
>    > # in the next `% Growth` is essential
>    > lm(`% Growth` ~ ., data=d)
>    
>    Call:
>    lm(formula = `% Growth` ~ ., data = d)
>    
>    Coefficients:
>    (Intercept)        `P/E`     `+-`TRUE
>           3.24         0.08        -2.44
>
> > If you find functions in base R that object to those names, I think we'd
> > like to fix them.
>
> A core R function that fails with odd names is reformulate():
>     > reformulate(c("P/E", "% Growth"), response="+-")
>     Error in parse(text = termtext) : <text>:1:16: unexpected input
>     1: response ~ P/E+% Growth
>                      ^

Thanks.  That one looks relatively easy to fix.

Duncan Murdoch
> It works you you add the `` inside the "" (for the termlabels, but not needed
> for the response argument):
>    > reformulate(c("`P/E`", "`% Growth`"), response="+-")
>    `+-` ~ `P/E` + `% Growth`
>
> 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 Duncan Murdoch
> > Sent: Thursday, February 28, 2013 1:46 PM
> > To: Jesus Munoz Serrano
> > Cc: r-help at r-project.org
> > Subject: Re: [R] Dealing with parentheses within variable names
> >
> > On 28/02/2013 11:08 AM, Jesus Munoz Serrano wrote:
> > > Dear all
> > >
> > > I'm having some problems with a data set that has parenthesis within the variable
> > names. A example of this kind of variable names is the following:
> > >
> > > 				fBodyGyroskewness()Z
> > >
> > > The case is that R is having a lot of troubles to identify the variable (probably it does
> > understand it like a function). I've tried (among other things) to remove the parenthesis
> > from the name using the following command:
> > >
> > > 				names(dataFrame) <- sub("()","", names(dataFrame))
> > >
> > > but It didn't work.  Sorry if it's a silly issue but I would really appreciate if anybody could
> > help me. Thank you very much.
> > R shouldn't have trouble with names like that, but a lot of packages
> > will (e.g. the ones that construct strings and call parse() on them).
> > If you find functions in base R that object to those names, I think we'd
> > like to fix them.  If the functions are in contributed packages, your
> > mileage may vary.
> >
> > Duncan Murdoch
> >
> > ______________________________________________
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