[R] generating a vector from clusters of logicals

[Troels Ring]

dear friends,
I have a vector of clusters of TRUE and FALSE like 
c(TRUE,TRUE,TRUE...,FALSE,FALSE,FALSE,....TRUE,TRUE...) and want to make 
that into a vector
of c(1,1,1,1...2,2,2,2,.....3,3,3,3) increasing the number assigned to each 
cluster as they change.
How would I do that ?

Best wishes

Troels Ring, Aalborg, Denmark