[datatable-help] Access to local variables in "j" expressions

[Johann Hibschman]

Hi Tom,

Thanks for taking the time to look into this so promptly. I've
installed that version, and it fixes my original problem. I'll keep
testing it and see if I run into any more issues.

I didn't get as much of a speed-up as I was hoping for the
time-intensive parts of my calculation, so I don't know how much
additional time I'll invest in it, but I'll keep experimenting for a
few days at least.

(I'm comparing, in effect, unlist(tapply(x, GroupID, cumsum)) to
dt[,list(out=cumsum(x)), by=GroupID]; they take more-or-less the same
time for me.)

-Johann



On Sat, May 8, 2010 at 2:17 PM, Short, Tom <TShort at epri.com> wrote:
> I checked in a fix for this bug on R-forge. It should be available for installation tomorrow as follows (R-forge has been a little flakey lately):
>
> install.packages("data.table",repos="http://r-forge.r-project.org")
>
> If you're able to try it, let me know if it works or causes other problems.
>
> - Tom
>
>
>
>> -----Original Message-----
>> From: datatable-help-bounces at lists.r-forge.r-project.org
>> [mailto:datatable-help-bounces at lists.r-forge.r-project.org]
>> On Behalf Of Short, Tom
>> Sent: Saturday, May 08, 2010 10:58 AM
>> To: Johann Hibschman; datatable-help at lists.r-forge.r-project.org
>> Subject: Re: [datatable-help] Access to local variables in
>> "j" expressions
>>
>> I've got a fix for this. It'll probably be a couple of days
>> before I can get it up to R-forge.
>>
>> - Tom
>>
>> > -----Original Message-----
>> > From: datatable-help-bounces at lists.r-forge.r-project.org
>> > [mailto:datatable-help-bounces at lists.r-forge.r-project.org]
>> > On Behalf Of Short, Tom
>> > Sent: Saturday, May 08, 2010 7:35 AM
>> > To: Johann Hibschman; datatable-help at lists.r-forge.r-project.org
>> > Subject: Re: [datatable-help] Access to local variables in "j"
>> > expressions
>> >
>> > I think it's a bug, Johann. I'll dig deeper. Thanks for
>> reporting it.
>> >
>> > - Tom
>> >
>> >
>> > > -----Original Message-----
>> > > From: datatable-help-bounces at lists.r-forge.r-project.org
>> > > [mailto:datatable-help-bounces at lists.r-forge.r-project.org]
>> > > On Behalf Of Johann Hibschman
>> > > Sent: Friday, May 07, 2010 4:53 PM
>> > > To: datatable-help at lists.r-forge.r-project.org
>> > > Subject: [datatable-help] Access to local variables in "j"
>> > expressions
>> > >
>> > > I'm just taking a look at data.table again, now that
>> 1.4.1 has been
>> > > released. I tried the following:
>> > >
>> > >   dt.test <- data.table(n=c("a","a","b"), x=1:3, key="n")
>> > >
>> > >   global.sum7 <- function (y) {
>> > >    sum(y) + 7
>> > >   }
>> > >
>> > >   test.1 <- function (dt) {
>> > >    local.sum7 <- global.sum7
>> > >    dt[, list(out=local.sum7(x)), by=n]
>> > >   }
>> > >
>> > >   test.1(dt.test)
>> > >
>> > >  This failed, with 'Error in eval(expr, envir, enclos) :
>> > > could not find function "local.sum7"'. Looking at the
>> > documentation, I
>> > > see:
>> > >
>> > >      The j expression 'sees' variables in the calling frame
>> > and above
>> > >      including .GlobalEnv, see the examples. This is base R
>> > >      functionality from eval() and with().
>> > >
>> > > That led me to think that the above would work. Is this a
>> > bug, or am I
>> > > not understanding something?
>> > >
>> > > Thanks,
>> > > Johann
>> > > _______________________________________________
>> > > datatable-help mailing list
>> > > datatable-help at lists.r-forge.r-project.org
>> > > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/d
>> > atatable-help
>> > >
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