r - Finding the index of first changes in the elements of a vector

Question

I have a vector v and I would like to find the index of first changes in elements of a vector in R. How can I do this? For example:

v = c(1, 1, 1, 1, 1, 1, 1, 1.5, 1.5, 2, 2, 2, 2, 2)

Answer 1

rle is a good idea, but if you only want the indices of the changepoints you can just do:

c(1,1+which(diff(v)!=0))
## 1 8 10