Find date difference based on condition - spotfire

Question

I have a table where data may be provided on monthly or yearly basis. The table data looks something as below:
Item Date Name
Class 1 12/31/2010 David
Class 1 12/31/2011 David
Class 1 12/31/2012 David
Class 1 12/31/2010 Moses
Class 1 12/31/2011 Moses
Class 1 12/31/2012 Moses
Class 1 01/31/2012 Shelly
Class 1 02/28/2012 Shelly
Class 1 03/31/2012 Shelly
Class 1 04/30/2012 Shelly
Class 1 05/31/2012 Shelly
Class 1 06/30/2012 Shelly
Class 1 07/31/2012 Shelly
Class 1 08/31/2012 Shelly
Class 1 09/30/2012 Shelly
Class 1 10/31/2012 Shelly
Class 1 11/30/2012 Shelly
Class 1 12/31/2012 Shelly
Class 2 01/31/2012 Shelly
Class 2 02/28/2012 Shelly
Class 2 03/31/2012 Shelly
Class 2 04/30/2012 Shelly
Class 2 05/31/2012 Shelly
Class 2 06/30/2012 Shelly
Class 2 07/31/2012 Shelly
Class 2 08/31/2012 Shelly
Class 2 09/30/2012 Shelly
Class 2 10/31/2012 Shelly
Class 2 11/30/2012 Shelly
Class 2 12/31/2012 Shelly
Class 2 01/31/2012 David
Class 2 02/28/2012 David
Class 2 03/31/2012 David
Class 2 04/30/2012 David
Class 2 05/31/2012 David
Class 2 12/31/2011 Soni
Class 2 12/31/2012 Soni
For a combination of Name and Item, either the date difference can be monthly or yearly. I want to include a calculated column named Flag. The condition to set flag is, if users had entered monthly data then set value as Yes else No.
So the rows with Class 1 - Shelly and all rows of Class 2 excluding Soni should be set as Yes.
Can anyone please guide me on this ? If I try Over and Intersect, for some of the columns, result is blank row.

Answer 1

Assuming you have at least 2 months of data for each Item / Name pairing, you can approach this two ways. Note, that unless you have 2 months of data you can't tell if, for the given year, you are receiving data monthly or yearly.
Insert Calculated Column DatePart("year",[Date]) as [Year]
Insert Calculated Column If(Count([Item]) OVER (Intersect([Name],[Item],[Year]))>1,"Yes","No") as [Flag]
Another expression that you may find useful will apply a rank / row number to each Year | Month | Item | Name pairing. Here is that expression which you can use to see how many months of data you have for that paring (using MAX()) or to do other aggregates / logical checks.
RankReal(Date(DatePart("year",[Date]),DatePart("month",[Date]),1),"asc",[Name],[Item],DatePart("year",[Date]),"ties.method=minimum") as [RowRank]