Yes I can. I suppose the actual inconsistency lies in rbind.data.frame then. It doesn't follow the same guarantee of "always outputs a data.table". Otherwise
rbind(NULL, NULL) and data.frame(NULL) would have the same result. Maybe I would wonder if calling it a "null data.table" is the right terminology, since it really is just an empty data.table. A null data.table would imply that is.null would be true. On Tue Oct 29 2013 at 2:11:30 PM, Eduard Antonyan <[email protected]> wrote: > perhaps you can use length() == 0 instead of is.null() for your purposes > > > On Tue, Oct 29, 2013 at 1:01 PM, Eduard Antonyan < > [email protected]> wrote: > > This is by design, and is not a bug. > > If you try > > data.table:::.rbind.data.table(NULL, NULL) > > in version 1.8.10 you will also get a 0-size data.table in agreement with > rbindlist (if you try the above in the very latest version, you will get an > error, and I may change that to be same as 1.8.10 - but it doesn't matter > much, as you can't get there unless you use ":::", and then all bets are > off anyway). Both are supposed to always return data.tables. > > The reason you're getting something else with rbind(NULL, NULL) is because > those NULL's are not data.tables, so a *different* rbind is called, which > has nothing to do with data.table. > > > > On Tue, Oct 29, 2013 at 12:47 PM, Chris Neff <[email protected]> wrote: > > Simple thing: > > dt <- rbindlist(list(NULL, NULL)) #dt is a data.table with 0 rows and > columns > > is.null(dt) # Prints false > > d <- rbind(NULL, NULL) #d is NULL > > is.null(d) # Prints true > > > I would expect the two to be equivalent. This bit me when I was relying > on !is.null(dt) before assigning other columns in the data.table. > rbindlist should return NULL in this case I would think. > > Is this working as intended? Or should I file a bug? > > _______________________________________________ > datatable-help mailing list > [email protected] > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help > > > >
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