Re: [R] use of NA's

From: Robert Kinley <KINLEY_ROBERT_at_lilly.com>
Date: Sat 06 Aug 2005 - 01:36:04 EST


with NAs it's always safest to use the construction

if(is.na(foo))

rather than

if(foo==NA)

cheers Bob Kinley

tom wright <tom@maladmin.com>
Sent by: r-help-bounces@stat.math.ethz.ch 05/08/2005 12:30

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r-help@stat.math.ethz.ch
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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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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 Received on Sat Aug 06 01:40:33 2005

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