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2012 Sep 17
6
count NAs per week
Even though I work with R since a year or so I still struggle with simple problems. I hope someone can help me with this. Been trying for days and am a little frustrated now. I have a data frame somewhat like the one bellow: dattrial<-data.frame(a=c(1,NA,rnorm(4,10)), Week=c(3,3,3,4,4,4)) I want to know how many NAs I have in week 3 and in week 4. -- View this message in context: