How to slice data from a middle index until the end without using `length` in R (like you can in python)?
Well this is confusing coming from a python background, but mylist[-1] seems to do the trick. The negative in this case can be read as "except," i.e. take everything except column 1. So colnames(iris)[-1] works to grab all but the first item.
Oh, and to exclude more items, treat it as a range that is excluded, so colnames(iris)[-2:-4] would keep only the first and all items after (and including) the fifth one.
For others coming from python, check out this nice slideshow comparing R to python.
In R tail(mylist, -2), has the same effect as mylist[2:] in Python.