repeating a number n times, then a different number for the remainder of the rows in R-CodePudding

I have a dataset where each row is a monthly observation of patients, monitoring whether they tested positive to a disease (status).

I know which month (i.e. row number for each ID - TimeToDx) they were diagnosed, and what I would like to do is have a binary indicator that switches from 0 to 1, starting from the observation month indicated in TimeToDx.

Basically I need to replicate 0 by the TimeToDx - 1, then for the remainder of the rows replicate 1 for each ID.

Here is some example data - without the status indicator filled:

 ID TimeToDx    Status
10425   2   
10425   2   
10425   2   
10425   2   
10667   3   
10667   3   
10667   3   
10667   3   
10667   3   
10686   2   
10686   2   
10686   2   
10686   2   
10686   2   
17096   5   
17096   5   
17096   5   
17096   5   
17096   5

Here is what I would like to see:

ID  TimeToDx    Status
10425   2       0
10425   2       1
10425   2       1
10425   2       1
10667   3       0
10667   3       0
10667   3       1
10667   3       1
10667   3       1
10686   2       0
10686   2       1
10686   2       1
10686   2       1
10686   2       1
17096   5       0
17096   5       0
17096   5       0
17096   5       0
17096   5       1

Any help would be much appreciated.

CodePudding user response：

Here's an approach with dplyr. Grouping within each ID, we compare the row within that group to the TimeToDx. TRUE x 1 = 1, FALSE x 1 = 0. Could alternately use mutate(Status = if_else(row_number() >= TimeToDx, 1, 0)).

library(dplyr)
df %>%
  group_by(ID) %>%
  mutate(Status = 1 * (row_number() >= TimeToDx)) %>%
  ungroup()