I have a polygon feature class and its corresponding attribute table that relates all silviculture treatments on USFS lands across the western United States:
The image above relates a sample of the attribute table for the polygon feature class described above. These entries contain equivalent values for “SUID”, “FACTS_ID” and two entries, “OBJECTID” = 510 and “OBJECTID” = 512, have equivalent values for the attribute field “ACTIVITY_CODE”.
“SUID” relates a discrete polygon that is effectively a discrete management unit. Specific actions on that spatial unit will only have consequence for my investigation if a certain amount of time has passed before an additional treatment has been executed. For example, “OBJECTID” = 510 and “OBJECTID” = 512 describe two “Patch Clearcut” treatments that only occurred a year apart. I need to interrogate how much time has passed between the same treatments on the same unit of land.
Logically: IF “SUID” AND “FACTS_ID” AND “ACTIVITY_CODE” are equivalent for any number of entries, determine the absolute value of the difference between the two years that the events occurred.
