It is because you don't know whether you want it or not. It is a bit more obvious with integer indexing, as in color[race]: if race is NA you don't know what color to put in, but the result should be the same length as race.
With logical indices, the behaviour is a bit annoying, but ultimately follows from the coercion rules: You might think that you could treat NA as FALSE (& the subset() function does just that), but then you'd get the problem that x[NA] would differ from x[as.integer(NA)] because NA is of mode "logical", lowest in the coercion hierarchy. -pd > On 26 Aug 2020, at 17:06 , Elham Daadmehr <[email protected]> wrote: > > Thanks guys. but I'm a bit confused. the input is the first column (z[,1] and > z1[,1]). > How is it possible that a subset of a non-NA vector, contains NA? > > On Wed, Aug 26, 2020 at 4:58 PM Eric Berger <[email protected]> wrote: > Good point! :-) > > > On Wed, Aug 26, 2020 at 5:55 PM peter dalgaard <[email protected]> wrote: > Offhand, I suspect that the NAs are in the 8th column. > > > On 26 Aug 2020, at 10:57 , Elham Daadmehr <[email protected]> wrote: > > > > Hi all, > > > > I have a simple problem. I get stuck in using the imported spss data (.sav) > > using "read.spss". > > I imported data (z) without any problem. After importing, the first column > > doesn't contain any "NA". but when I choose a subset of it (like: > > z[z[,8]=="11"|z[,8]=="12"|z[,8]=="14",]), lots of NA appears (even in the > > first column). > > > > The (.sav) file is the output of Compustat (WRDS). > > > > It is terrible, I can't find the mistake. > > > > Thank you in advance for your help, > > Elham > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > [email protected] mailing list -- To UNSUBSCRIBE and more, see > > 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. > > -- > Peter Dalgaard, Professor, > Center for Statistics, Copenhagen Business School > Solbjerg Plads 3, 2000 Frederiksberg, Denmark > Phone: (+45)38153501 > Office: A 4.23 > Email: [email protected] Priv: [email protected] > > ______________________________________________ > [email protected] mailing list -- To UNSUBSCRIBE and more, see > 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. -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Office: A 4.23 Email: [email protected] Priv: [email protected] ______________________________________________ [email protected] mailing list -- To UNSUBSCRIBE and more, see 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.
