R: How to identify the first occurrence of a specific value of a variable grouped by ID

Question

I have a dataset in form of a Diary - i.e. i have multiple entries for the same ID. Apart from that, I have a categorical variable (Yes/no) that indicates whether the event occured or not.

ID <-  c(1,1,1,2,2,2,2,3,3,3,3,3,3)
event <- c("No", "No", "No", "Yes", "No", "No", "Yes", "Yes", "Yes", "No", "No", "Yes", "Yes") 
df <- data.frame(ID, event)

ID   event   
 1    No
 1    No
 1    No
 2    Yes
 2    No
 2    No
 2    Yes
 3    Yes
 3    Yes
 3    No
 3    No
 3    Yes
 3    Yes

I now want to delete those entries until the first "No", so every ID should start with a "No". However, after the first "No" there can still be a "Yes". So the desired output i want is:

ID   event   
 1    No
 1    No
 1    No
 2    No
 2    No
 2    Yes
 3    No
 3    No
 3    Yes
 3    Yes

Does anybody know how to achieve this? Thanks in advance for your time!

Answer 1

We can get the first "No" using which.max and select all the rows from there till last row.

library(dplyr)
df %>% group_by(ID) %>% slice(which.max(event == 'No') : n())
#Also
#df %>% group_by(ID) %>% slice(which(event == 'No')[1] : n())

#      ID event
#   <dbl> <chr>
# 1     1 No   
# 2     1 No   
# 3     1 No   
# 4     2 No   
# 5     2 No   
# 6     2 Yes  
# 7     3 No   
# 8     3 No   
# 9     3 Yes  
#10     3 Yes  

Answer 2

Try:

library(dplyr)

df %>%
  group_by(ID) %>%
  filter(cumsum(event == 'No') >= 1)

Output:

# A tibble: 10 x 2
# Groups:   ID [3]
      ID event
   <int> <fct>
 1     1 No   
 2     1 No   
 3     1 No   
 4     2 No   
 5     2 No   
 6     2 Yes  
 7     3 No   
 8     3 No   
 9     3 Yes  
10     3 Yes