use of NA's
To test for 'NA' you shouldn't use '=='. Use 'is.na()' instead. -roger
tom wright wrote:
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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Roger D. Peng http://www.biostat.jhsph.edu/~rpeng/