pyspark: calculating row deltas

[Franc Carter]

Hi,

I have a DataFrame with the columns

     ID,Year,Value

I'd like to create a new Column that is Value2-Value1 where the
corresponding Year2=Year-1

At the moment I am creating  a new DataFrame with renamed columns and doing

   DF.join(DF2, . . . .)

 This looks cumbersome to me, is there abtter way ?

thanks


-- 
Franc