I'm working with R and my dataset looks like this :
| Day | Test1 | Test2 | Test 3 | 
|---|---|---|---|
| 1 | 25 | NA | 30 | 
| 2 | NA | 12 | 35 | 
- Code for the input dataframe:
df1 <- data.frame(Day = c(1,2),
                  Test1 = c(25,NA),
                  Test2 = c(NA,12),
                  Test3 = c(30, 35))
is there a way to change it to this structure :
| Day | Test | Values | 
|---|---|---|
| 1 | Test1 | 25 | 
| 1 | Test2 | NA | 
| 1 | Test3 | 30 | 
| 2 | Test1 | NA | 
| 2 | Test2 | 12 | 
| 2 | Test3 | 35 | 
 
     
    