Compare same values in different months

[Lokesh_5045]

I have the data like below for all months.

ID	Month	Value
A	December	1
B	December	2
C	December	3
D	December	4
A	November	5
B	November	2
C	November	1

I need to flag only present month IDs by comparing with previous month same IDs. I cannot do this in script since my previous month selection is dynamic from drop down list. Suppose if I select November from drop down list, the data should appear like below.

ID	Month	Value	Flag
A	December	1	Decrease
B	December	2	Same
C	December	3	Increase
D	December	4	New

Flagging is based on comparison of value of same ID of selected month.
{December} C   >   {November} C -----> Increase

[AronC]

If you show the fields ID, Value and Flag and leave out month from your table, you can use this expression

if(Sum(Value)>sum({<Month, MonthId={"$(=max(MonthId)-1)"}>}Value),'increased','decreased')

For it to work you need to create Ids for your month backend. If you have a calendar table, then you just create you id field like:

load *, autonumber(Month) as MonthId

Hope it helped you out.

[Lokesh_5045]

@AronC , Thank you for your reply.
My current month is max of my date field and I have saved into a variable. In present example, it is December.
My selected month is based on month input from variable input from front end. In present example, it is November.
I shouldn't change my backend script and my current visualization.
Please suggest me. This can be done using set analysis imo. But, I am not getting any ideas here.

[AronC · Accepted solution]

If you dont want to use monthId you could do everything in the set expression as in below. I prefer flags though because it makes everything easier and more clear. But you can use the below expression.

if(Sum(Value)>sum({<Month={"$(=month(addmonths(max(Date),-1)))"}>}Value),'increased','decreased')

If you want to show the selected month in the table as well you could just use an expression.

Expression for showing the month: month(Min(Date))

Good luck and please mark as solution if it works out for you.