Hi, > dt[, list(x=list(I(x)), y=list(I(y))), by=list(grp = x %% 3)]
this seems to work and is pretty natural. I guess the idea was to wrap the result twice in list(). Thanks. _______________________________________________ datatable-help mailing list [email protected] https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
