[datatable-help] Playing nice(r) with S4?

[Matthew Dowle]

Hi Steve,

I don't know much about S4 but seems like a good idea, no objections from
me either.

Please click 'request to join' button on R-Forge project page for
data.table, add some tests to the end of test.data.table.R, add something
to the NEWS file, run 'R CMD build' and 'R CMD check', and (if ok) commit.

Matthew


> Hi Tom,
>
> On Tue, Nov 23, 2010 at 10:53 AM, Tom Short <tshort.rlists at gmail.com>
> wrote:
>> On Tue, Nov 23, 2010 at 10:33 AM, Steve Lianoglou
>> <mailinglist.honeypot at gmail.com> wrote:
>>> Hi all,
>>>
>>> Can we include some functions/declarations so that data.table objects
>>> can be used in S4 classes?
>>
>> Steve, S4 has always scared me off, but if we can do something easy
>> like that to help users, we probably should.
>
> At the start, it did for me as well, but I think I (largely) have the
> hang of it ... I wouldn't say I'm an expert, though.
>
>> Do we have to require any other packages?
>
> Not as far as I know. Usually a package that defines S4 classes and
> such is required to import the 'methods' package, but I'm not sure if
> it's necessary here.
>
> I simply just `svn up`d my data.table repo and added the AllS4.R as
> written above, then `R CMD INSTALL`ed it, and everything was kosher --
> no warnings or anything and it works as expected.
>
>> My only comment is related to the data.table(from) in the setAs
>> function. Do you want that to be as.data.table(from)? The latter is
>> probably faster but does less error checking and auto-conversions of
>> columns.
>
> Sure -- I'm largely indifferent on that, so whatever is more idiomatic
> for the data.table devs probably will make the most sense.
>
> Maybe for consistency sake, one would add:
>
> setAs("data.table", "data.frame"), function(from) {
>   as.data.frame(from) ## or whatever
> })
>
> So we can go back the other way and convert a data.table back to a
> data.frame via `as(dt, "data.frame")`
>
> -steve
>
> --
> Steve Lianoglou
> Graduate Student: Computational Systems Biology
>  | Memorial Sloan-Kettering Cancer Center
>  | Weill Medical College of Cornell University
> Contact Info: http://cbio.mskcc.org/~lianos/contact
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