flextable: How to merge rows with duplicate values for some columns

Question

I'm making a table using flextable(). I would like to merge cells with duplicated srdr_id.

Given these data:

test <- structure(list(srdr_id = c("175124", "175124", "172545", "172545", 
"172609", "172609", "172609"), full_name = c("TAU", "MI", "TAU", 
"MI", "TAU", "MI", "MI"), article_arm_name = c("Control", "WISEteens", 
"Assessed control", "Intervention", "Control", "Computer BI", 
"Therapist BI"), arm_number = c(1L, 2L, 1L, 2L, 1L, 2L, 3L)), row.names = c(NA, 
-7L), class = c("tbl_df", "tbl", "data.frame"))


  srdr_id full_name article_arm_name arm_number
  <chr>   <chr>     <chr>                 <int>
1 175124  TAU       Control                   1
2 175124  MI        WISEteens                 2
3 172545  TAU       Assessed control          1
4 172545  MI        Intervention              2
5 172609  TAU       Control                   1
6 172609  MI        Computer BI               2
7 172609  MI        Therapist BI              3

I can do it with the following code - but would like to simplify the multiple merge_at() statements.

flextable(test) %>% theme_box() %>% 
           merge_at(i = 1:2, j = 1) %>% 
           merge_at(i = 3:4, j = 1) %>% 
           merge_at(i = 5:7, j = 1) 

Unfortunately, the simple solution, merge_v(j = ~srdr_id), no longer is sufficient when I add another column which is duplicated across common srdr_id's.

test_2 <- structure(list(srdr_id = c("175124", "175124", "172525", "172525", 
"172545", "172545", "172609", "172609", "172609"), substances = c("alcohol", 
"alcohol", "alcohol", "alcohol", "cannabis", "cannabis", "alcohol\n cannabis\n other drugs", 
"alcohol\n cannabis\n other drugs", "alcohol\n cannabis\n other drugs"
), full_name = c("TAU", "MI", "TAU", "MI (parent)", "TAU", "MI", 
"TAU", "MI", "MI"), article_arm_name = c("Control", "WISEteens", 
"Treatment as usual", "Brief MI (b-MI)", "Assessed control", 
"Intervention", "Control", "Computer BI", "Therapist BI")), row.names = c(NA, 
-9L), class = c("tbl_df", "tbl", "data.frame"))

# A tibble: 9 x 4
  srdr_id substances                         full_name   article_arm_name  
  <chr>   <chr>                              <chr>       <chr>             
1 175124  alcohol                            TAU         Control           
2 175124  alcohol                            MI          WISEteens         
3 172525  alcohol                            TAU         Treatment as usual
4 172525  alcohol                            MI (parent) Brief MI (b-MI)   
5 172545  cannabis                           TAU         Assessed control  
6 172545  cannabis                           MI          Intervention      
7 172609  "alcohol\n cannabis\n other drugs" TAU         Control           
8 172609  "alcohol\n cannabis\n other drugs" MI          Computer BI       
9 172609  "alcohol\n cannabis\n other drugs" MI          Therapist BI    

Answer 1

Wow - I missed the obvious solution for the simple case. Question has been edited with a more realistic (nested) dataset.

test_ft <- flextable(test) %>% theme_box() %>%  merge_v(j = ~srdr_id)