Is there a dplyr equivalent to data.table::rleid?

Question

data.table offers a nice convenience function, rleid for run-length encoding:

library(data.table)
DT = data.table(grp=rep(c(\"A\", \"B\", \"C\",         


        

Answer 1

A simplification (involving no additional package) of the approach used by the OP could be:

DT %>%
 mutate(rleid = with(rle(grp), rep(seq_along(lengths), lengths)))

   grp value rleid
1    A     1     1
2    A     2     1
3    B     3     2
4    B     4     2
5    C     5     3
6    C     6     3
7    C     7     3
8    A     8     4
9    B     9     5
10   B    10     5

Or:

DT %>%
 mutate(rleid = rep(seq(ls <- rle(grp)$lengths), ls))