How to find a value near a dynamic date?

[peterstalberg]

Hi,

In an app I have a set of three dimensions (PRODUCT_ID,  PRICE,  DATETIME). What would be the correct chart expression for PRICE_AT_180 to show the the listed price closest before 180 days after the first listing?  

I have tried several variations of =FirstSortedValue(EST_100, EST_DATETIME_FR+180) but nothing gives the desired result. Assistance on this would be highly appreciated. Thanks//Peter

INPUT

PRODUCT_ID	PRICE	DATETIME
Product A	15 000	2011-09-07 05:36:11.36113611
Product A	25 000	2011-10-30 06:43:31.43314331
Product A	75 000	2012-01-28 10:52:03.523523
Product A	165 000	2014-10-14 09:30:06.306306
Product A	130 858	2015-06-23 03:45:14.45144514
Product B	5 000	2018-01-19 09:59:07.597597
Product B	10 000	2018-03-22 16:27:13.27132713
Product B	15 000	2018-05-07 16:22:33.22332233
Product B	22 000	2019-01-07 16:22:37.22372237

RESULT

PRODUCT_ID	PRICE_AT_180	DATETIME
Product A	75 000	2012-01-28 10:52:03.523523
Product B	15 000	2018-05-07 16:22:33.22332233