Conditional increment tidyverse

Question

I\'ve been googling quite unsuccessfully how to increment conditionally in tidyverse. What I want to do is check if value in a column is greater than some x, and if

Answer 1

This can be done using a cumulative sum, which increments each time the value is greater than 100, for example:

df_x %>% 
  group_by(id) %>% 
  mutate(increment = 1 + cumsum(time > 100))

# A tibble: 9 x 3
# Groups:   id [4]
     id  time increment
  <dbl> <dbl>     <dbl>
1    1.   20.        1.
2    1.   30.        1.
3    1.  101.        2.
4    2.   33.        1.
5    3.   50.        1.
6    3.  101.        2.
7    3.   30.        2.
8    3.  110.        3.
9    4.   30.        1.

I used 1 + cumsum(...) in order to start the first group from 1 instad of 0. Not that a group might start with a 2 if the first value is >100 in a given id-group.