Hi, On Wed, Apr 18, 2012 at 6:26 AM, Chris Neff <[email protected]> wrote: > I would agree that a empty data table is the expected result I would > have had. [snip]
Completely agree w/ Chris' synopsis (below) and +1 on making the change. -steve > If I do > > DT[, sum(v), by=x] > > I always expect a two column data.table with columns "x" and "V1" > (which is sum(x)). In SQL this would read > > SELECT > x, > SUM(v) > FROM DT > GROUP BY x > > > So with DT[y<1, sum(v), by=x] we have > > SELECT > x, > SUM(v) > FROM DT > WHERE y < 1 > GROUP BY x > > Now in any SQL dialect I work with, if WHERE y < 1 didn't return any > rows, then the result of this would be a 0 row selection. I believe > that is what it should be with data.table as well: a 0-row data.table > with columns "x" and "V1". > > This is a valid bug IMO, and should definitely be fixed. > On Wed, Apr 18, 2012 at 3:32 AM, Matthew Dowle <[email protected]> wrote: >> Dear datatablers, >> >> This seems like a valid bug report. Any reasons why we shouldn't make >> this change? >> >> https://r-forge.r-project.org/tracker/?func=detail&atid=975&aid=1945&group_id=240 >> >> Matthew >> >> >> >> _______________________________________________ >> datatable-help mailing list >> [email protected] >> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help > _______________________________________________ > datatable-help mailing list > [email protected] > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help -- 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
