Create calcualted field as v1=If(isnull([value obj]) then "Y" else" N"
Now take count(([v1]) and In filters restrict V1 ="N"
What have you tried so far to create the desired calculation?
There are likely many different ways to do this but one thing I tried was to create a simple Show/Hide calculation and place that on the Filter Shelf (see below):
IF [Value] = 0 THEN 'Hide' ELSE 'Show' END
If we then drag the Date field onto the text shelf, we can change the aggregation to Count Distinct and that should give us the count you are looking for.
If you're strictly looking for a calculation and want to avoid the filter shelf, we may have to go a different route.
I've attached the .twbx for your review.
CountDate.twbx 11.6 KB
Thanks Shin! Much appreciated.
Thanks for your help everyone!