Select two column regions in R

Question

I'm sure there is a simple solution, but I can't work it out and googling isn't helping me.

If I want to find the max of each row within the boundaries I do this:

temp.df$S1max <- apply(S1[135:175], 1, max)

But how can I apply this to regions outside of that bounds? This doesn't work:

temp.df$S1mean <- apply(S1[0:135, 175:300], 1, mean)

Thanks

@VincentBonhomme there is not going to be a better answer than yours. You should post it as such. :) — Therkel, Jun 15 '16 at 11:32
@Daniel when you apply over a vector, consider using the the `sapply` function. :) `sapply(S1[135:175],max)` — Therkel, Jun 15 '16 at 11:44
@Daniel I cannot explain it better than the top answer to the question [R Grouping functions: sapply vs. lapply vs. apply. vs. tapply vs. by vs. aggregate](http://stackoverflow.com/a/7141669/3560695). — Therkel, Jun 15 '16 at 15:04
haha, well that looks thorough and something that I need to work my way through. Thanks! — Daniel, Jun 15 '16 at 16:39

score 4 · Accepted Answer · answered Jun 15 '16 at 11:36

4

You can use negative indexing:

apply(S1[-c(135:175)], 1, mean)

answered Jun 15 '16 at 11:36

Vincent Bonhomme

1 Answers1