This function calculates the average age of the grass
     
    
    calc_grass_age(ID, B_LU_BRP)
 
    
    Arguments
- ID
- (numeric) The ID of the field 
- B_LU_BRP
- (numeric) The crop code (gewascode) from the BRP 
 
    
    Value
    The age of the grassland within a crop rotation plan. A numeric value.
     
    
    Details
    The function assumes that the order of crop codes are descending, so the latest year is on top.
     
    
    Examples
    calc_grass_age(ID = rep(1,5), B_LU_BRP = c(1091,265,256,256,1091))
#> [1] 0 1 0 0 0
calc_grass_age(ID = rep(1,5), B_LU_BRP = c(265,265,265,265,1091))
#> [1] 4 3 2 1 0