Hello I have a dataframe such as

```
Groups COL1         
G1     Unknown_RNA  
G1     Unknown_RNA  
G1     A            
G1     A            
G1     Unknown_RNA
G2     B
G2     A 
G2     B 
G3     Unknown_RNA
G3     A
G4     Unknown_RNA
G4     Unknown_RNA
G4     Unknown_RNA

```

Then I should keep the most representated value in `df$COL1` and put it in a `consensus_COL1` column without taking into account the value `Unknown_RNA` (exept when there is only this value in the group.

Here I should get :

```
Groups COL1         consensus_COL1         
G1     Unknown_RNA  A
G1     Unknown_RNA  A
G1     A            A            
G1     A            A     
G1     Unknown_RNA  A 
G2     B            B
G2     A            B 
G2     B            B 
G3     Unknown_RNA  A
G3     A            A
G4     Unknown_RNA  Unknown_RNA 
G4     Unknown_RNA  Unknown_RNA 
G4     Unknown_RNA  Unknown_RNA 

```

So far I only know how to keep the most representated value with :

```
 df %>% filter(COL1 != "") %>%
  group_by(Groups) %>%
  add_count(COL1) %>%
  top_n(1, n) %>%
  distinct(consensus_COL1 = COL1) %>%
  right_join(df)

```

but I do not known how to add the `Unknown_RNA` issue

here are the data

```
structure(list(Groups = structure(c(1L, 1L, 1L, 1L, 1L, 2L, 2L, 
2L, 3L, 3L, 4L, 4L, 4L), .Label = c("G1", "G2", "G3", "G4"), class = "factor"), 
    COL1 = structure(c(3L, 3L, 1L, 1L, 3L, 2L, 1L, 2L, 3L, 1L, 
    3L, 3L, 3L), .Label = c("A", "B", "Unknown_RNA"), class = "factor")), class = "data.frame", row.names = c(NA, 
-13L))

```