[R] Rule for accessing attributes?

[Tribo Laboy]

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?
>  >
>
>
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>  >
>  >
>
>
>