Howdy, On Fri, Jan 20, 2012 at 8:43 PM, Matthew Dowle <[email protected]> wrote: > Hi Steve, > > Adding 'drop' does sound better. The original gripe was its default, not > drop itself I suppose. It might be handy when j isn't a single name, > too; e.g., > >> DT > a v > [1,] A 1 > [2,] A 2 > [3,] B 3 > [4,] B 4 > [5,] B 5 >> setkey(DT,a) >> DT[c("A","B"),sum(v)]$V1 # current > [1] 3 12 >> DT[c("A","B"),sum(v),drop=TRUE] # future > [1] 3 12 > > When j doesn't return a vector and drop=TRUE was supplied then it should > warn?; e.g., > > DT[c("A","B"),list(sum(v),min(v)),drop=TRUE] # warning, ignoring drop
It *feels* like it should warn, right? I double checked to see what base R data structures do (matrices and data.frames) and they don't warn in this scenario. So, I guess while I'm in favor of firing the warning in these situations, I think it's probably better to just do as base R does. -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 _______________________________________________ datatable-help mailing list [email protected] https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
