Subtract from previous year total

[rtun]

Hello all,

I have a total for the year 2021 and I'm working on an expression for future years until 2030 by subtracting from the previous year something like;

if 2021 has a total of 1000

then 2022 has a total of 1000-100=900

2023 has a total of 800

2024 has a total of 700

Can anyone help me ? I’m struggling to find the correct solution for a few days.

Thanks in advance for your help.

[vinieme12]

can you post some sample data? also confirm if you are trying to achieve this at a chart level or script

[rtun]

It is a chart.  I used the expression below;

if (Year = 2021, sum ({$<fType ={'DDG'}>}fAmount),
if (Year > 2021, sum({$<Year> - 1}fAmount) - 100))

Basically, I just want to come up with an expression that gives me a subtraction of 100 from the previous year total. 

[vinieme12]

Try below

Current Year = sum ({<fType ={'DDG'}, Year={"$(=Max(Year))"}>}fAmount)

Previous Year = sum ({<fType ={'DDG'}, Year={"$(=Max(Year)-1)"}>}fAmount)

Previous Year - 100 = sum ({<fType ={'DDG'}, Year={"$(=Max(Year)-1)"}>}fAmount) - 100