Okay I appreciate the help, and I appreciate the FAQ reminder. I will read
the r-help posting guide. I'm relatively new to using the support systems
around R. So far everyone has been really helpful.

I'm confused as to which data.table "list" I should be using.
http://lists.r-forge.r-project.org/pipermail/datatable-commits/ doesn't
appear to be correct. Or just directly sending an email to all of you?

Thanks again,
Rob



On Wed, Mar 3, 2010 at 6:05 AM, Matthew Dowle <mdowle@mdowle.plus.com>wrote:

>
> I'd go a bit further and remind that the r-help posting guide is clear :
>
>  " For questions about functions in standard packages distributed with R
> (see the FAQ Add-on packages in R), ask questions on R-help.
> If the question relates to a contributed package , e.g., one downloaded
> from
> CRAN, try contacting the package maintainer first. You can also use
> find("functionname") and packageDescription("packagename") to find this
> information. ONLY send such questions to R-help or R-devel if you get no
> reply or need further assistance. This applies to both requests for help
> and
> to bug reports. "
>
> The "ONLY" is in bold in the posting guide. I changed the bold to capitals
> above for people reading this in text only.
>
> Since Tom and I are friendly and responsive, users of data.table don't
> usually make it to r-help. We'll follow up this one off-list.  Please note
> that Rob's question is very good by the rest of the posting guide, so no
> complaints there, only that it was sent to the wrong place.  Please keep
> the
> questions coming, but send them to us, not r-help.
>
> You do sometimes see messages to r-help starting something like "I have
> contacted the authors/maintainers but didn't hear back,  does anyone know
> ...".   To not state that they had would be an implicit request for further
> work by the community (for free) to ask if they had. So its not enough to
> contact the maintainer first, but you also have to say that you have as
> well, and perhaps how long ago too would be helpful.  For r-forge projects
> I
> usually send any question to everyone on the project (easy to find) or if
> they have a list then to that.
>
> HTH
> Matthew
>
>
> "Tom Short" <tshort.rlists@gmail.com> wrote in message
> news:fd27013a1003021718w409acb32r1281dfeca559314a@mail.gmail.com...
> On Tue, Mar 2, 2010 at 7:09 PM, Rob Forler <rforler@uchicago.edu> wrote:
> > Hi everyone,
> >
> > I have the following code that works in data frames taht I would like tow
> > ork in data.tables . However, I'm not really sure how to go about it.
> >
> > I basically have the following
> >
> > names = c("data1", "data2")
> > frame = data.frame(list(key1=as.integer(c(1,2,3,4,5,6)),
> > key2=as.integer(c(1,2,3,2,5,6)),data1 = c(3,3,2,3,5,2), data2=
> > c(3,3,2,3,5,2)))
> >
> > for(i in 1:length(names)){
> > frame[, paste(names[i], "flag")] = frame[,names[i]] < 3
> >
> > }
> >
> > Now I try with data.table code:
> > names = c("data1", "data2")
> > frame = data.table(list(key1=as.integer(c(1,2,3,4,5,6)),
> > key2=as.integer(c(1,2,3,2,5,6)),data1 = c(3,3,2,3,5,2), data2=
> > c(3,3,2,3,5,2)))
> >
> > for(i in 1:length(names)){
> > frame[, paste(names[i], "flag"), with=F] = as.matrix(frame[,names[i],
> > with=F] )< 3
> >
> > }
>
> Rob, this type of question is better for the package maintainer(s)
> directly rather than R-help. That said, one answer is to use list
> addressing:
>
> for(i in 1:length(names)){
>    frame[[paste(names[i], "flag")]] = frame[[names[i]]] < 3
> }
>
> Another option is to manipulate frame as a data frame and convert to
> data.table when you need that functionality (conversion is quick).
>
> In the data table version, frame[,names[i], with=F] is the same as
> frame[,names[i], drop=FALSE] (the answer is a list, not a vector).
> Normally, it's easier to use [[]] or $ indexing to get this. Also,
> fname[i,j] <- something assignment is still a bit buggy for
> data.tables.
>
> - Tom
>
> Tom Short
>
> ______________________________________________
> R-help@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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