[R] Set attributes for object known by name

[Bert Gunter]

Well, it can be done without a temporary variable, but I'm not sure you
would want to.
Anyway...

## simplified example
> a <- 1
> vname <- "a"
> eval(substitute(attr(x,"b") <- "hi", list( x = as.name(vname))))
> a
[1] 1
attr(,"b")
[1] "hi"


Cheers,
Bert


Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Wed, Oct 10, 2018 at 9:48 PM Peter Langfelder <peter.langfelder using gmail.com>
wrote:

> oops, I think the right code would be
>
> x = get(varname)
> attr(x, "foo") = "bar"
> assign(varname, x)
>
> On Wed, Oct 10, 2018 at 9:30 PM Peter Langfelder <
> peter.langfelder using gmail.com>
> wrote:
>
> > I would try something like
> >
> > x = get(myvarname)
> > attr(x, "foo") = "bar"
> > assign(varname, x)
> >
> > HTH,
> >
> > Peter
> >
> > On Wed, Oct 10, 2018 at 9:15 PM Marc Girondot via R-help <
> > r-help using r-project.org> wrote:
> >
> >> Hello everybody,
> >>
> >> Has someone the solution to set attribute when variable is known by
> name ?
> >>
> >> Thanks a lot
> >>
> >> Marc
> >>
> >> Let see this exemple:
> >>
> >> # The variable name is stored as characters.
> >>
> >> varname <- "myvarname"
> >> assign(x = varname, data.frame(A=1:5, B=2:6))
> >> attributes(myvarname)
> >>
> >> $names
> >> [1] "A" "B"
> >> $class
> >> [1] "data.frame"
> >> $row.names
> >> [1] 1 2 3 4 5
> >>
> >> # perfect
> >>
> >> attributes(get(varname))
> >>
> >> # It works also
> >>
> >> $names
> >> [1] "A" "B"
> >> $class
> >> [1] "data.frame"
> >>
> >> $row.names
> >> [1] 1 2 3 4 5
> >>
> >> attributes(myvarname)$NewAtt <- "MyAtt"
> >>
> >> # It works
> >>
> >> attributes(get(varname))$NewAtt2 <- "MyAtt2"
> >> Error in attributes(get(varname))$NewAtt2 <- "MyAtt2" :
> >>    impossible de trouver la fonction "get<-"
> >>
> >> # Error...
> >>
> >> ______________________________________________
> >> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> >> 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.
> >>
> >
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>

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