Selecting 4 consecutive rows after conditioın-CodePudding

I have this data

ratings <- data.frame(Rating = c(0,99,99,99,99,99,99,99,0,99,99,99,99,99,99,99,99,99,99,99),
Trial = c(1,NA,NA,NA,NA,NA,NA,NA,2,NA,NA,NA,NA,NA,3,NA,NA,NA,NA,NA))

Rating Trial 
0        1      
99      NA      
99      NA      
99      NA      
99      NA   
99      NA   
99      NA      
99      NA      
0       2       
99      NA      
99      NA      
99      NA          
99      NA          
99      NA      
1       3       
99      NA      
99      NA      
99      NA    
99      NA    
99      NA

I want to select the four consecutive rows after the second trial.

What I've tried

ratings |> 
 mutate(var = ifelse(lag(Trial, n = 4L) == 2, 1, 0))

But, reasonably so, I am selecting only the 4th row.

What I want to get to:

Rating Trial var
0        1    0     
99      NA    0     
99      NA    0     
99      NA    0     
99      NA    0     
99      NA    0     
99      NA    0     
99      NA    0     
0       2     0     
99      NA    1     
99      NA    1     
99      NA    1         
99      NA    1         
99      NA    0     
1       3     0     
99      NA    0     
99      NA    0     
99      NA    0     
99      NA    0     
99      NA    0

Any ideas? Thanks.

CodePudding user response：

ratings <- data.frame(Rating = c(0,99,99,99,99,99,99,99,0,99,99,99,99,99,99,99,99,99,99,99),
Trial = c(1,NA,NA,NA,NA,NA,NA,NA,2,NA,NA,NA,NA,NA,3,NA,NA,NA,NA,NA))

library(dplyr, warn.conflicts = FALSE)

ratings %>% 
  mutate(var = replace(rep(0, n()), which(Trial == 2)   1:4, 1))
#>    Rating Trial var
#> 1       0     1   0
#> 2      99    NA   0
#> 3      99    NA   0
#> 4      99    NA   0
#> 5      99    NA   0
#> 6      99    NA   0
#> 7      99    NA   0
#> 8      99    NA   0
#> 9       0     2   0
#> 10     99    NA   1
#> 11     99    NA   1
#> 12     99    NA   1
#> 13     99    NA   1
#> 14     99    NA   0
#> 15     99     3   0
#> 16     99    NA   0
#> 17     99    NA   0
#> 18     99    NA   0
#> 19     99    NA   0
#> 20     99    NA   0

^{Created on 2022-08-07 by the reprex package (v2.0.1.9000)}