Select last observation from longitudinal data?

I can play this game. I ran some benchmarks on differences between lapply, sapply, and by, among other things. It appears to me that the more you're in control of data types and the more basic the operation, the faster it is (e.g. , lapply is generally faster than sapply, and as.

Numeric(lapply(...)) is going to be faster, also). With that in mind, this produced the same results as above and may be faster than the rest.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.