This short & neat post describes an interesting solution on how to use filter to remove null values from a calculated field.
Scenario: Users would like to have an option to filter null values from a calculated field.
Error: To filter null values, the calculated field is put in the Rows pane, converted to discrete, and selected ‘Show Filter’. However, if ‘Null’ is de-selected from the filter, an error message ‘invalid filter predicate’ will appear.
Fortunately, there’s a work-around solution for this bug (which is noticed in Tableau Desktop 9.2 and 10).
Solution: Put calculated field in Rows pane, change to Discrete, & select 'Show Filter'. Change filter to 'Exclude Values'. In the filter, select Null to exclude null values.
