[datatable-help] Question About data.table package

[Scott Murray]

Hello,

I am using your data.table R package to apply a function to subsets of a large data set.  The performance of the package is absolutely fantastic, so I thank you for developing it.  I am running into one issue however, that I hope you can answer.

I have posted the question on stackoverflow.com.  If you prefer to make the answer public, the link is:
http://stackoverflow.com/questions/10527072/using-data-table-package-inside-my-own-package

The question is as follows:
I am trying to use the data.table package inside my own package. MWE is as follows:
I create a function, test.fun, that simply creates a small data.table object, and then sums the "Val" column grouping by the "A" column. The code is
test.fun<-function ()
{
    library(data.table)
    testdata<-data.table(A=rep(seq(1,5), 5), Val=rnorm(25))
    setkey(testdata, A)
    res<-testdata[,{list(Ct=length(Val),Total=sum(Val),Avg=mean(Val))},"A"]
    return(res)
}
When I create this function in a regular R session, and then run the function, it works as expected.
> res<-test.fun()
data.table 1.8.0  For help type: help("data.table")
> res
     A Ct      Total        Avg
[1,] 1  5 -0.5326444 -0.1065289
[2,] 2  5 -4.0832062 -0.8166412
[3,] 3  5  0.9458251  0.1891650
[4,] 4  5  2.0474791  0.4094958
[5,] 5  5  2.3609443  0.4721889
When I put this function into a package, install the package, load the package, and then run the function, I get an error message.
> library(testpackage)
> res<-test.fun()
data.table 1.8.0  For help type: help("data.table")
Error in `[.data.frame`(x, i, j) : object 'Val' not found
Any help is very much appreciated.
Thanks,
Scott
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.r-forge.r-project.org/pipermail/datatable-help/attachments/20120510/b9542b0c/attachment.html>