Chart calculation

[salto]

Hello community,

I come back with another inter-record question.

From this data table (well, something similar to this):

Date	Key	Amount
2015/10/31	A	100
2015/10/31	B	50
2015/11/30	A	7
2015/12/31	A	45
2015/11/30	B	33
2015/12/31	B	75
2016/01/31	A	88
2016/01/31	B	44
2016/02/29	A	22
2016/02/29	B	234

I need a chart with an expression that, for every item, shows the Amount difference in that month versus Amount value in december of the previous year:

Key	Date	Amount2
A	2016/02/29	22-45 (22 is current month value, 45 is the value in 2015/12/31)
B	2016/02/29	234-75 (234 is current month value, 75 is the value in 2015/12/31)

How can I get the value for 2015/12/31?

Many thanks in advance!

[sunny_talwar]

For Key A, 88 seems to be on 2016/01/31. Is that a typo?

[sunny_talwar · Accepted solution]

Not sure which one you want, but may be this

[Anonymous]

Hi

for current month   KEY A

Sum({$<[Date]={"$(=Date(Max(Date), 'YYYY/DD/MM'))"},Key=A>} Amount)

For December of previous year KEY A

Sum({$<[Date]={"$(=Date(yearend(Max(Date),-1) 'YYYY/DD/MM'))"},Key=A>} Amount)