tibco spotfire 中的月末/年末数据

Question

I have the following dataset in tibco spotfire:

Original data

I want to bring the amount of item in the beginning of each month for each row and get the following result:

Image

Any suggestions?

Answer 1

I could do it via an intermediate column (as Spotfire's OVER does not accept expressions).

First calculate the year and month like this: (assuming the format of your date is known and stable) [YearMonth] is:

Integer(Concatenate(Substring(String([Date]),7,4),Substring(String([Date]),4,2)))

then your [Previous Month] is:

Max([Amount]) over (Intersect(Previous([YearMonth]),[BRANCH],[CLASS]))

and your [Diff] is:

[Amount] - [Previous Month]