Thanks a lot for the explaination. Much appreciated. :-)

On Thu, Dec 27, 2012 at 10:31 PM, William Dunlap <wdunlap@tibco.com> wrote:

> > Can you please elaborate. What are the negatives about the method
>
> Here are a few examples of eval(parse(text=paste())) failing:
>   > cvtest <- list("Test-1"=1, Bozo=2, "Joe's Test"=3)
>   >
>   > lambda.rule <- "Test-1"
>   > eval(parse(text=paste0("cvtest$", lambda.rule))) # want 1
>   [1] 0
>   >
>   > lambda.rule <- "Joe's Test"
>   > eval(parse(text=paste0("cvtest$", lambda.rule))) # want 3
>   Error in parse(text = paste0("cvtest$", lambda.rule)) :
>     <text>:1:11: unexpected INCOMPLETE_STRING
>   1: cvtest$Joe's Test
>              ^
>
> and here is an example of "$" giving a suboptimal result:
>   > cvtest$B # want NULL (there is no component named "B")
>   [1] 2
>
> "[[" gives the correct result in all cases:
>   > lambda.rule <- "Test-1"
>   > cvtest[[lambda.rule]]
>   [1] 1
>   > lambda.rule <- "B"
>   > cvtest[[lambda.rule]]
>   NULL
>   > lambda.rule <- "Bozo"
>   > cvtest[[lambda.rule]]
>   [1] 2
>   > lambda.rule <- "Joe's Test"
>   > cvtest[[lambda.rule]]
>   [1] 3
>
> Also, I find it hard to read code involving eval(parse(text=paste(...))).
>
> Bill Dunlap
> Spotfire, TIBCO Software
> wdunlap tibco.com
>
>
> > -----Original Message-----
> > From: r-help-bounces@r-project.org [mailto:r-help-bounces@r-project.org]
> On Behalf
> > Of Heramb Gadgil
> > Sent: Thursday, December 27, 2012 2:44 AM
> > To: Uwe Ligges
> > Cc: Thomas Stewart; r-help
> > Subject: Re: [R] how to get a value from a list (using paste function)?
> >
> > I am not sure why "Never ever!"
> >
> > Can you please elaborate. What are the negatives about the method
> >
> > Warm Regards,
> > Heramb M. Gadgil
> >
> >
> > On Thu, Dec 27, 2012 at 3:50 PM, Uwe Ligges <
> ligges@statistik.tu-dortmund.de
> > > wrote:
> >
> > >
> > >
> > > On 27.12.2012 08:09, Heramb Gadgil wrote:
> >
> > >> eval(parse(text=paste0("**cvtest$",lambda.rule)))
> > >>
> > >
> > > No, never ever!
> > >
> > > There is an R idiom made for it:
> > >
> > > cvtest[[lambda.rule]]
> > >
> > > Uwe Ligges
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >  I hope this works.
> > >>
> > >> On Wed, Dec 19, 2012 at 12:57 AM, Thomas Stewart
> > >> <tgs.public.mail@gmail.com>**wrote:
> > >>
> > >>  Soyeon-
> > >>>
> > >>> A possible solution:
> > >>>
> > >>> get(lambda.rule,envir=**list2env(cvtest))
> > >>>
> > >>>
> > >>> On Tue, Dec 18, 2012 at 12:34 PM, Soyeon Kim <yunni0731@gmail.com>
> > >>> wrote:
> > >>>
> > >>>  Dear my R friends,
> > >>>>
> > >>>> I want to get a number from a list using paste function.
> > >>>> In my example,
> > >>>> lambda.rule <- "lambda.1se"
> > >>>> cvtest is a list (result from cv.glmnet)
> > >>>> and
> > >>>> cvtest$lambda.1se
> > >>>> [1] 1.308973
> > >>>>
> > >>>> I want to call the value using paste function.
> > >>>> I used get function but there was an error.
> > >>>> test <-  get(paste("cvtest$",lambda.**rule, sep=""))
> > >>>> Error in get(paste("cvtest$", lambda.rule, sep = "")) :
> > >>>>    object 'cvtest$lambda.1se' not found
> > >>>>
> > >>>> Do you guys know how to solve this issue?
> > >>>>
> > >>>> Thank you so much in advance and merry Christmas!
> > >>>>
> > >>>> Soyeon
> > >>>>
> > >>>> ______________________________**________________
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> > >>>> http://www.R-project.org/**posting-guide.html<http://www.R-
> > project.org/posting-guide.html>
> > >>>> and provide commented, minimal, self-contained, reproducible code.
> > >>>>
> > >>>>
> > >>>>
> > >>>>
> > >>>          [[alternative HTML version deleted]]
> > >>>
> > >>> ______________________________**________________
> > >>> R-help@r-project.org mailing list
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> > help<https://stat.ethz.ch/mailman/listinfo/r-help>
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> > project.org/posting-guide.html>
> > >>> and provide commented, minimal, self-contained, reproducible code.
> > >>>
> > >>>
> > >>         [[alternative HTML version deleted]]
> > >>
> > >> ______________________________**________________
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> > help<https://stat.ethz.ch/mailman/listinfo/r-help>
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> >
> >       [[alternative HTML version deleted]]
> >
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