set.seed(1)
M1 <- sample(c("N","Y"), 10, replace = T)
M2 <- sample(c("N","Y"), 10, replace = T)
M3 <- sample(c("N","Y"), 10, replace = T)
M1[5] <- NA; M2[7] <- NA; M3[3] <- NA
meds <- data.frame(M1,M2,M3)
meds$counts.NA <- apply(meds, 1, function(x) { y <- x=="Y"; sum(y)})
meds$counts.noNA <- apply(meds, 1, function(x) { y <- x=="Y"; sum(y, na.rm = T)})