This is an example:
I did it one by one the routine I desire.
k1=c(1,2,3,4,5)
k2=c(10,20,30,40,50)
k3=c(3,5,7,9,11)
k4=c(1,NA,1,1,NA)
kk=data.frame(k1,k2,k3,k4)
listv=c("k1","k2","k3") # list of variables
kk$k1_d=ifelse(kk$k1>3,1,NA)
kk$k2_d=ifelse(kk$k2>3,1,NA)
kk$k3_d=ifelse(kk$k3>3,1,NA)
kk
So, you can see the logic in creating a variables adding a "_d".
Now, imagine a list with many variables ( over 50).
Can I write a loop?
Or maybe using apply?