If all is TRUE (or just all.x or all.y is TRUE) then result is keyed. Why the key is not set when all is FALSE (default) I'm not sure. Tom - can you remember? Something to do with NAs in keys seems to ring a bell.
Matthew "Joseph Voelkel" <[email protected]> wrote in message news:[email protected]... > See code below. When two data tables are merged (by their key > variable(s)), that key disappears in the resulting table. While this is > probably not strictly a bug, it would seem that the user would most likely > want to preserve the key in the output (especially if just enlarging the > original data table, e.g. dt2<-merge(dt1,dt2).) > > >> dt1<-data.table(a=1:6,b=11:16,key="a") >> dt2<-data.table(a=1:6,c=21:26,key="a") >> dt3<-merge(dt1,dt2) >> >> > NAME NROW MB COLS KEY > [1,] dt1 6 1 a,b a > [2,] dt2 6 1 a,c a > [3,] dt3 6 1 a,b,c > Total: 3MB > > > Joseph G. Voelkel, Ph.D. > Professor, Center for Quality and Applied Statistics > Kate Gleason College of Engineering > Rochester Institute of Technology > V 585-475-2231 > F 585-475-5959 > [email protected] _______________________________________________ datatable-help mailing list [email protected] https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
