Re: [R] Rule for accessing attributes?

From: Tribo Laboy <tribolaboy_at_gmail.com>
Date: Thu, 27 Mar 2008 14:17:49 +0900

Thanks Christos, for your reply and for sharing how to access the attributes?, slots? in a shorthand notation with @, but after reading the help for @, I became even more confused. Is there any place that has collected wisdom on R indexing?

On Thu, Mar 27, 2008 at 1:35 PM, Christos Hatzis <christos_at_nuverabio.com> wrote:
> You need to use the '@' operator to directly access attributes (not
> elements) of objects:
>
> > lst_at_names
> [1] "x" "y" "z"
>
>
> See ?'@' for more details.
>
> -Christos
>
> > -----Original Message-----
> > From: r-help-bounces_at_r-project.org
> > [mailto:r-help-bounces_at_r-project.org] On Behalf Of Tribo Laboy
> > Sent: Thursday, March 27, 2008 12:16 AM
> > To: r-help_at_r-project.org
> > Subject: [R] Rule for accessing attributes?
> >
>
>
> > Hi !
> >
> > I am a new user and quite confused by R-indexing.
> >
> > Make a list and get the attributes
> > lst <- list(x = 1:3, y = 4:6, z = 7:9)
> > attributes(lst)
> >
> > This returns:
> >
> > $names
> > [1] "x" "y" "z"
> >
> > I can easily do:
> >
> > nm <-names(lst)
> >
> > or
> >
> > nm <-attr(lst,"names")
> >
> > which both return the assigned names of the named list 'lst',
> > but why then this doesn't work:
> >
> > lst$names
> >
> > ?
> >
> > I am confused ... Moreover, I noticed that some of the objects (e.g.
> > plot objects returned by ggplot) also have attributes when
> > queried by the 'attributes' function, but they are accessible
> > by the $ notation.
> > (e.g.
> >
> > xydf <- data.frame(x = 1:5, y = 11:15)
> > plt <- ggplot(data = xydf, aes(x = x,y = y)) + geom_point()
> > attributes(plt)
> >
> > Now we can change the title:
> >
> > plt$title <- "My Title"
> > plt
> >
> > So is it some inconsistency or am I missing something important?
> >
>
>
> > ______________________________________________
> > 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.
> >
> >
>
>
>



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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. Received on Thu 27 Mar 2008 - 07:58:46 GMT

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