Search adjacent number groups in a list

Question

This is a duplicate question, with the exception of R, not Python.

I would like to identify groups of contiguous (some call them continuous) integers in a list where duplicate entries are considered as existing within the same range. Therefore:

myfunc(c(2, 3, 4, 4, 5, 12, 13, 14, 15, 16, 17, 17, 20)) 

returns:

 min max 2 5 12 17 20 20 

Although any output format will be fine. My current brute force method, for-loop is pretty slow.

(Apologies if I could easily reformulate Python's answer, and I'm stupid!)

Answer 1

Just use diff :

 x = c(2, 3, 4, 4, 5, 12, 13, 14, 15, 16, 17, 17, 20) start = c(1, which(diff(x) != 1 & diff(x) != 0) + 1) end = c(start - 1, length(x)) x[start] # 2 12 20 x[end] # 5 17 20