818 and 819 created On Thu, Sep 18, 2014 at 4:34 PM, Arunkumar Srinivasan <[email protected] > wrote:
> Thanks. It'd also be great if you could add an issue for adding the > documentation. > On NA non-matching, yes you could add an FR, there isn't one to my > recollection. However much of this year has been spent on internal order > and binary search in tweaking quite a lot of things. So I'd not be > surprised if it is not attended to anytime soon. > > Arun > > From: Juan Manuel Truppia <[email protected]> <[email protected]> > Reply: Juan Manuel Truppia <[email protected]>> <[email protected]> > Date: September 18, 2014 at 9:14:42 PM > To: Arunkumar Srinivasan <[email protected]>> <[email protected]> > Cc: [email protected] > <[email protected]>> > <[email protected]> > Subject: Re: [datatable-help] NA in joins > > It might help, specially where data.table is compared to SQL. However, I > think that having merge (and maybe [.data.table) have an argument to avoid > NA matching. Is there a FR already created for this? I can create it > otherwise > > On Thu, Sep 18, 2014 at 4:00 PM, Arunkumar Srinivasan < > [email protected]> wrote: > >> In base R `NA` matches `NA` alone, and `NaN` matches `NaN` alone: >> match(NA, c(1:5, NA)) >> # [1] 6 >> >> data.table matches, through binary search, by design, in the same way. And >> in `?match`, there's this line: "Exactly what matches what is to some >> extent a matter of definition." In some operations it may not make sense. >> But, by design, we do consider Inf = Inf, -Inf = -Inf, NaN = NaN and NA = >> NA always. Do you think it'd help tp state this explicitly in `?data.table`? >> >> >> Arun >> >> From: Juan Manuel Truppia <[email protected]> <[email protected]> >> Reply: Juan Manuel Truppia <[email protected]>> <[email protected]> >> Date: September 18, 2014 at 6:14:56 PM >> To: [email protected] >> <[email protected]>> >> <[email protected]> >> Subject: [datatable-help] NA in joins >> >> Hi, this must have been discussed before, but I couldn't find >> anything. >> >> In my opinion, NA shouldn't join with anything, including other NA (as to >> mirror what we expect from SQL, where NULL doesn't join with NULL). >> >> However, with data.table, NA matches other NA. >> >> I.e, this should return an empty data.table >> >> data.table(idx = NA_real_, key = "idx")[data.table(idx = NA_real_, val = >> "a", key = "idx"), nomatch = 0] >> >> Let's assume that we can't change this behavior, would it be possible to >> add a parameter to avoid NA matching NA in [.data.table and merge? >> _______________________________________________ >> datatable-help mailing list >> [email protected] >> >> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help >> >> >
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