How can I count runs in a sequence?

Question

In R, what would be the most efficient/simplest way to count runs of identical elements in a sequence?

For example, how to count the numbers of consecutive zeros in a sequence of non-negative integers:

x <- c(1,0,0,0,1,0,0,0,0,0,2,0,0) # should give 3,5,2 

Answer 1

Use rle():

y <- rle(c(1,0,0,0,1,0,0,0,0,0,2,0,0)) y$lengths[y$values==0]