The "names" slot is not part of the basic vector types/classes.
If you want to extend named lists, extend the class "namedList":
> getClass("namedList")
Class "namedList" [package "methods"]
Slots:
Name: .Data names
Class: list character
Extends:
Class "list", from data part
Class "vector", by class "list", distance 2
Known Subclasses: "listOfMethods"
> setClass("myNamedList", contains = "namedList")
[1] "myNamedList"
>
> mm <- new("myNamedList", list(a=1,b=2))
> mm
An object of class "myNamedList"
$a
[1] 1
$b
[1] 2
On 3/4/11 3:30 AM, Renaud Gaujoux wrote:
Hi,
I want to extend the type list, but it looks like the names are not
handled properly (in the show method), not the [ method. See below for
code example.
I imagine this comes from the S3/S4 mixing, but I would like to
understand and the recommended work around (that avoid redefining all
the list methods [, $, etc...).
Thank you.
Bests,
Renaud
# define S4 class that inherits from list
setClass('A', contains='list')
# nothing to say when one creates an object with an unnamed list
x <- new('A', list(1,2,3))
x
# set the names: seems ok but they are not printed
names(x) <- letters[1:3]
names(x)
x
# same thing if one put the S3 .Data slot
names(x@.Data) <- letters[4:6]
names(x)
x
# the subsetting works but returns a list instead of the expected object
of class A
class(x[1])
> sessionInfo()
R version 2.12.1 (2010-12-16)
Platform: x86_64-pc-linux-gnu (64-bit)
locale:
[1] LC_CTYPE=en_ZA.utf8 LC_NUMERIC=C LC_TIME=en_ZA.utf8
LC_COLLATE=en_ZA.utf8 LC_MONETARY=C LC_MESSAGES=en_ZA.utf8
LC_PAPER=en_ZA.utf8
[8] LC_NAME=C LC_ADDRESS=C LC_TELEPHONE=C LC_MEASUREMENT=en_ZA.utf8
LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
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