Hello all. I have a long-format database that looks like this:
id wave var1 var2
1 1 85 .
1 2 . .
1 3 87 .
1 4 . 5
2 1 . .
2 2 92 .
2 3 76 .
2 4 . 8
I need a variable that is generated using var1 and var2 (let's call it var3). Now, I would only keep observations from wave 4 because that's where I have the measurement for var2, but that would be useless because I wouldn't have any measurement for var1 in wave 4.

So my question is, is there a way to generate a new variable (let's say var1_new) that is equal to the most recent measurement of var1 for each id? So that I would have something like the following:
id wave var1 var2 var1_new
1 4 . 5 87
2 4 . 8 76
Any help is appreciated, thank you.