Thanks, the dataframe, is indeed clever at preserving its dimensions. I'll try your solution with the real data
On Tue, Jun 22, 2010 at 12:23 M, Petr PIKAL <petr.pi...@precheza.cz> wrote: > Hi > > r-help-boun...@r-project.org napsal dne 22.06.2010 08:28:04: > > > The following dataframe will illustrate the problem > > > > > > DF<-data.frame(name=rep(1:5,each=2),x1=rep("A",10),x2=seq(10,19,by=1),x3=rep > > (NA,10),x4=seq(20,29,by=1)) > > DF$x3[5]<-50 > > > > # we have a data frame. we are interested in the columns x2,x3,x4 which > > contain sparse > > # values and many NA. > > DF > > name x1 x2 x3 x4 > > 1 1 A 10 NA 20 > > 2 1 A 11 NA 21 > > 3 2 A 12 NA 22 > > 4 2 A 13 NA 23 > > 5 3 A 14 50 24 > > 6 3 A 15 NA 25 > > 7 4 A 16 NA 26 > > 8 4 A 17 NA 27 > > 9 5 A 18 NA 28 > > 10 5 A 19 NA 29 > > > > # we have a list of "target values that we want to search for in the > data > > frame > > # if the value is in the data frame we want to keep it there, otherwise, > > replace it with NA > > > > targets<-c(11,12,13,16,19,50,27,24,22,26) > > # so we apply a test by column to the last 3 columns using the "in" test > > # this gives us a mask of whether the data frame 'contains' elements in > the > > # target list > > > > mask<-apply(DF[,3:5],2, "%in%" ,targets) > > mask > > > > x2 x3 x4 > > [1,] FALSE FALSE FALSE > > [2,] TRUE FALSE FALSE > > [3,] TRUE FALSE TRUE > > [4,] TRUE FALSE FALSE > > [5,] FALSE TRUE TRUE > > [6,] FALSE FALSE FALSE > > [7,] TRUE FALSE TRUE > > [8,] FALSE FALSE TRUE > > [9,] FALSE FALSE FALSE > > [10,] TRUE FALSE FALSE > > > > # and so DF[2,3] is equal to 11 and 11 is in the target list, so the > mask is > > True > > # now something like DF<- ifelse(mask==T,DF,NA) is CONCEPTUALLY what I > want > > Data frames are quite clever in preserving their dimensions. I would do > > mask=data.frame(a=TRUE, b=TRUE, !mask) > > to add column 1 and 2 > > and > > DF[mask]<-NA > > Regards > Petr > > > > to do > > in the end I'd Like a result that looks like > > > > name x1 x2 x3 x4 > > 1 1 A NA NA NA > > 2 1 A 11 NA NA > > 3 2 A 12 NA 22 > > 4 2 A 13 NANA > > 5 3 A NA 50 24 > > 6 3 A NA NA NA > > 7 4 A 16 NA 26 > > 8 4 A NA NA 27 > > 9 5 A NA NA NA > > 10 5 A 19 NA NA > > > > Ive tried forcing the DF and the mask into vectors so that ifelse() > would > > work > > and have tried "apply" using ifelse.. without much luck. any thoughts? > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > > and provide commented, minimal, self-contained, reproducible code. > > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.