R: creating a categorical variable from a numerical variable and custom/open-ended/single-valued intervals

Question

I often find myself trying to create a categorical variable from a numerical variable + a user-provided set of ranges.

For instance, say that I have a data.frame wi

Answer 1

Use cut(), already:

df$VCAT2 <- cut(df$V, c(0,9.999,10,20,Inf), labels=F)

Notice the trick I pull to define a very small bin at 10:

• (and if you need that bin to be infinitesimally narrow, use 10 - 10*.Machine$double.eps)
• you can manually define your desired labels '(0,10)','[10,10]',(10,20), [20,Inf]' with the cut(..., labels) argument.