How to get the latest two events on a specific window using Flint?

[kant777]

How to get the latest two events using this library?

Say I have the following

time    | price
---------------
1000L | 40
2000L | 20
3000L | 80
4000L | 10
5000L | 60
6000L | 30

I want to do operations like

1. Get the last 2 events or last 4 events in the past 6 hours
2. Difference in price for the last two events in 6 hours.

How to do this using Flint? I can write my own udf and solve this but I am wondering if there is any inbuilt function that is already available?

[dgrnbrg]

I've done this by leftJoining the data frame to itself shifted forward w/ a tolerance, but that's hideously slow. I think that you could use addPastWindows for 6 hours, and then use a UDF on that.