Im trying to modify some data and have the following data now:
df <- data.frame(year = c(2010,2011,2010,2011),A = c(10,11,10,11),B = c(11,12,11,12))
  year        A         B
1 2010        10        11
2 2011        11        12
3 2010        10        11
4 2011        11        12
I want it to look like this, but do not know how to do it. Can anyone help me?
  company year   Variable
1   A      2010  10           
2   A      2011  11            
3   B      2010  11             
4   B      2011  12      
 
    