Agreed, SO is much more suited for this and previous questions. On Thu, Jul 23, 2015 at 2:19 PM, Frank Erickson <[email protected]> wrote:
> I think you want > > DT[,(newName):=do.call(paste,c(list(sep="_"),.SD)),.SDcols=colNames] > > This is probably the sort of thing that would come naturally after > studying all the vignettes and such on the site: > https://github.com/Rdatatable/data.table/wiki/Getting-started Dunno that > you want to be sending so much stuff to everyone on a mailing list. Your > call, though. > > --Frank > > On Thu, Jul 23, 2015 at 3:13 PM, statquant3 <[email protected]> wrote: > >> R) data.table(x=letters[1:5],y=rnorm(5),z=LETTERS[1:5]) >> x y z >> 1: a 0.5551301186 A >> 2: b 0.1092535710 B >> 3: c -2.4319115661 C >> 4: d 1.6915588561 D >> 5: e -1.5163715976 E >> >> colNames = c('y','z') >> newName = 't' >> >> How do I add a column 't' such that t:=paste(y,x,sep='_') >> >> x y z t >> 1: a 0.5551301186 A 0.5551301186_A >> 2: b 0.1092535710 B 0.1092535710_B >> 3: c -2.4319115661 C ... >> 4: d 1.6915588561 D ... >> 5: e -1.5163715976 E ... >> >> >> >> >> -- >> View this message in context: >> http://r.789695.n4.nabble.com/What-s-the-trick-to-paste-several-columns-together-in-one-tp4710266.html >> Sent from the datatable-help mailing list archive at Nabble.com. >> _______________________________________________ >> 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 >
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