More elegant way to return a sequence of numbers based on booleans?

Question

Here\'s a sample of booleans I have as part of a data.frame:

atest <- c(FALSE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, FALSE, TRUE, TRUE,

Answer 1

Here's one way to do it, using handy (but not widely-known/used) base functions:

> sequence(tabulate(cumsum(!atest)))
 [1]  1  2  3  4  5  6  7  8  9 10  1  2  3  4  5  6  7  8  9 10  1

To break it down:

> # return/repeat integer for each FALSE
> cumsum(!atest)
 [1] 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3
> # count the number of occurrences of each integer
> tabulate(cumsum(!atest))
[1] 10 10  1
> # create concatenated seq_len for each integer
> sequence(tabulate(cumsum(!atest)))
 [1]  1  2  3  4  5  6  7  8  9 10  1  2  3  4  5  6  7  8  9 10  1