On: Introduction to Statistical Learning

[fizixer]

- R: the mean function is already created

- C: You will create the mean function

It's the difference between using a calculator and knowing how to multiply two 5 digit numbers with pen and paper.

You might say, "Oh but we can do that in R". Well, if you start doing that one function at a time, very soon you find yourself with R grinding to a halt.

[disgruntledphd2 → fizixer]

Go look at the R source for mean sometime (you want the base function). It's not as simple as one might imagine.

[cinntaile → fizixer]

If you want to you can recreate the mean function in R as well, so why would you choose to do it in another language if your goal is to learn R?

[dunefox → cinntaile]

No good reason for C/D/... other than the wanting to learn the particular language. Otherwise, use R or Julia to stay in the scientific domain.