Hello,
steven mosher wrote:
# create a matrix with some random NAs in it
m<-matrix(NA,nrow=15,ncol=14)
m[,3:14]<-52
m[13,9]<-NA
m[4:7,8]<-NA
m[1:2,5]<-NA
m[,2]<-rep(1800:1804, by=3)
y<-order(m[,2])
m<-m[y,]
m[,1]<-rep(1:3,by=5)
# what we want is a result that looks like this
1800 3 3 2 3 3 2 3 3 3 3 3 3
1801 3 3 2 3 3 2 3 3 3 3 3 3
1802 3 3 3 3 3 3 2 3 3 3 3 3
1803 3 3 3 3 3 2 3 3 3 3 3 3
1804 3 3 3 3 3 2 3 3 3 3 3 3
This should work:
apply(m[, 3:14], 2,
function(x) tapply(x, m[,2], function(x) sum(!is.na(x))))
It uses tapply inside of apply to break up the groups by m[, 2].
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