with NAs it's always safest to use the construction
if(is.na(foo))
rather than
if(foo==NA)
cheers Bob Kinley
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
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