Mark > Ok, I have the following data: > > data["A"] = [1,2,4,10,50] > > and I want to get: > > data["new"] = [?, 1, 2, 6, 40] >>> A = [1,2,4,10,50] >>> ['?']+[a-b for b,a in zip(A,A[1:])] ['?', 1, 2, 6, 40] -- Emile van Sebille emile at fenx.com ---------