Robert Kinley wrote: >with NAs it's always safest to use the construction > >if(is.na(foo)) > >rather than > >if(foo==NA) > >cheers Bob Kinley > > > > And if it is not clear why, try:
> NA == NA [1] NA > Kjetil >tom wright <[EMAIL PROTECTED]> >Sent by: [EMAIL PROTECTED] >05/08/2005 12:30 > >To >r-help@stat.math.ethz.ch >cc > >Subject >[R] use of NA's > > > > > > >Can someone please explain why this works: > > > >>>d<-c(0,2,3,2,0,3,4,0,0,0,0,0) >>>d.mat<-matrix(data=d,nrow=4,ncol=3,byrow=TRUE) >>>for(i in 1:length(d.mat[1,])){ >>> >>> >>+ d.mat[,i][d.mat[,i]==0]<-mean(d.mat[,i][d.mat[,i]>0]) >>+ } >> >> > >Whereas: > > > >>d<-c(0,2,3,2,0,3,4,0,0,0,0,0) >>d.mat<-matrix(data=d,nrow=4,ncol=3,byrow=TRUE) >>d.mat[d.mat==0]<-NA >>for(i in 1:length(d.mat[1,])){ >> >> >+ d.mat[,i][d.mat[,i]==NA]<-mean(d.mat[,i],na.rm=TRUE) >+ } >dosnt > >Thanks >Tom > >______________________________________________ >R-help@stat.math.ethz.ch mailing list >https://stat.ethz.ch/mailman/listinfo/r-help >PLEASE do read the posting guide! >http://www.R-project.org/posting-guide.html > > > [[alternative HTML version deleted]] > >______________________________________________ >R-help@stat.math.ethz.ch mailing list >https://stat.ethz.ch/mailman/listinfo/r-help >PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > > > > > -- Kjetil Halvorsen. Peace is the most effective weapon of mass construction. -- Mahdi Elmandjra -- Internal Virus Database is out-of-date. Checked by AVG Anti-Virus. ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html