Calculate "New Users" based on last login

[Anonymous]

Very new to DAX, this may be a simple task.

I have a table with Conversation ID, USerID, and Login TimeStamp. I am trying to show a trending chart of users, by Login TS.

Conversation ID	User ID	TimeStamp
123	Sam	March 10, 2020 23:45:00
123	Sam	March 10, 2020 23:59:00
456	Vimes	December 11, 2019 12:34:00
789	Vimes	December 12, 2019 07:36:00
567	Vimes	January 10, 2020 10:34:00

My calculation to show "New Users" requires me to identify the unique users who have had at least 30 hours expired since their last login. So, for the example above, Sam would not be considered a New User for March 10. Vimes would not be a new user for December 12 (since it has been less than 30 hours since his last login on December 11), but Vimes would be a new user for January 10. How can I achieve this? I was thinking of adding a calculated column with "Previous TS" for each user, and then take the difference between the two TS, but so far have been unable to achieve this.

Thank you!

[HotChilli · Accepted solution]

A column for the hours since last login:

HoursSinceLastLogin = VAR _user = TableCons[User ID]
                      VAR _time = TableCons[TimeStamp] 
RETURN
   DATEDIFF( CALCULATE(MAX(TableCons[TimeStamp]), FILTER(TableCons, TableCons[User ID] = _user && TableCons[TimeStamp] < _time)), TableCons[TimeStamp] , HOUR)