[R] Proba( Ut+2=1 / ((Ut+1==1) && (Ut==1))) ?

[vincent]

Dear all,

First I apologize if my question is quite simple,
but i'm very newbie with R.

I have vectors of the form v = c(1,1,-1,-1,-1,1,1,1,1,-1,1)
(longer than this one of course).
The elements are only +1 or -1.

I would like to calculate :
- the frequencies of -1 occurences after 2 consecutives -1
- the frequencies of +1 occurences after 2 consecutives +1

It looks probably something like :
Proba( Ut+2=1 / ((Ut+1==1) && (Ut==1)))

could someone please give me a little hint about how
i should/could begin to proceed ?

Thanks
(Thanks also to the R creators/contributors, this soft
seems really great !)