Fill down constant value, add 1 when condition is met in dplyr

Question

I have a dataframe as follows:

step   state   
1      active
2      active
       break
1      active
2      error
3      active
       break
1      active

I want to create a new column where I fill down a constant value of 1, then add 1 to the constant fill every time a "break" row is reached, which would make the dataframe look like.

step   state     n
1      active    1
2      active    1
       break     2
1      active    2
2      error     2
3      active    2
       break     3
1      active    3

Any solution using dplyr or base r would be helpful. Thanks

Answer 1

We can use cumsum with %in% and mutate.

library(dplyr)

dat2 <- dat %>%
  mutate(n = cumsum(state %in% "break") + 1)
dat2
#   step  state n
# 1    1 active 1
# 2    2 active 1
# 3    2  break 2
# 4    1 active 2
# 5    2  error 2
# 6    3 active 2
# 7    3  break 3
# 8    1 active 3

Data

dat <- read.table(text = "step   state   
1      active
2      active
2       break
1      active
2      error
3      active
3       break
1      active",
                  header = TRUE)