[R] find jumps in vector of repeats

[Benton, Paul]

Hello all,

I'm not really sure how to search for this in google/Rseek so there is probably a command to do it. I also know I could write an apply loop to find it but thought I would ask all you lovely R gurus. 

I have a very long vector (length=1855190) it looks something like this

1111...2222...3333....etc so it would be something equivalent of doing:
rep(c(1,2,3,4,5), c(10,30,24,65,3))

How can I find the index of where the step/jump is? For example using the above I would get an index of 0, 10, 40, 64, 129

Any help would be greatly appreciated.

Cheers,

Paul