The name of my variables looks like this:

df <- data.frame(var_NA = 1:10, var = 11:20, var_v2 = 21:30)

Except I have lots of variables. The key feature is that for every “mother” variable var, there are many “child” variables with different names (like var_NA and var_v2). Some “mothers” have more “children” than other. One thing is fixed though: there is always a child with suffix _NA.

What I want is to order columns like this:

1. mother variable
2. _NA child
3. the rest (if available)
4. mother variable
5. _NA child
6. the rest (if available)
   .
   .
   .

I’ve given up trying with select(ends_with()), relocate() and other comments. This is probably done best with regex, of which I am totally ignorant. Any ideas?