Hi There 

I am a new user of "R" and having a few problems

a<-c("2001-02-1","NA","NA")
a<-as.Date(a,format = "%Y-%m-%d")

b<-c("2001-03-1","2001-03-2","2001-03-3")
b<-as.Date(b,format = "%Y-%m-%d")

c<-data.frame(a,b)

I would like to write an if statement where if "a" is not null return
"a", if "a" is null (NA) return "b" less two days. Could someone help?.


Andrew  



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