Distance between timestamps that belong to same column

Hi,

I have a column called "date" which is timestamp format:

I want to calculate the distance in weeks between 1st date and 2nd date, then 2nd date and 3rd date then 3rd date and 4th date.. and so on.

After calculating the distance in weeks for each and every one, I want to average the distances.

Is there any way I can do that in Knime. And specifically in the Groupby variable in Pattern based aggregation?

I tried time difference but is not exactly what I need.