Count consecutive TRUE values within each block se

Question

This question already has answers here:

Create counter within consecutive runs of certain values (5 answers)

Closed 2 years ago.

Similar questions have been asked, and I've been trying to cobble the answers (rle, cumsum, etc.) together from various ones but it's taking me hours and I'm still not getting there.

I have a data set with a column containing TRUE / FALSE values only, e.g.:

x <- c(FALSE, FALSE, TRUE, TRUE, TRUE, FALSE, TRUE, FALSE, TRUE, TRUE, FALSE)

For each set of continuous TRUE values, I want to count the number of TRUEs in that set. The FALSE values can be ignored, i.e. I want an output for the above data that looks like this:

x2 <- c(0, 0, 1, 2, 3, 0, 1, 0, 1, 2, 0)

Answer 1

There's always interesting ways to employ cumsum to do this sort of counter:

x[x] <- ave(x[x], cumsum(!x)[x], FUN=seq_along)
x
# [1] 0 0 1 2 3 0 1 0 1 2 0