Hello, I'm trying to generate unique IDs for building footprints. I want them to be begin with the Unique ID of the grid cell in which they are located. But I don't want the number to be very long (the building shapefile has over 1 million features). For example, I want the 3 buildings in Grid Cell F1A2 to be labeled F1A2001, F1A2002, F1A2003...and the 4 buildings in Grid Cell F1A3 to be labeled F1A3001, F1A3002, F1A3003, F1A3004. So far, I've created the grid with a unique ID for each cell, and I've spatially joined this to the building footprint, so each building has an associated grid cell name. I'm stuck on how how to autocalculate a field with numbers that reset each time the Grid Cell ID changes. Any ideas on how I can achieve that?
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