kevin-matthews

Weighted Population?

Discussion created by kevin-matthews on Dec 1, 2011
Latest reply on Dec 2, 2011 by curtvprice
I have a set of 15,000 grid points and a raster of Census population.  For each point, I need to calculate a buffer radius that sums to a certain population value (say 50,000 for example) by incrementally expanding a buffer at each point to achieve that threshold.  Does anyone know how I can accomplish this type of analysis?

Alternately, I have been trying to do this in using the "Near Table" tool in the "Proximity ArcToolBox".  In this case, I have 15,000 grid points and approximately 110,000 census block centroids with population attached.   I am successful in that I can create a buffer that "overshoots" the block points required to sum to 50,000 person.  My next step is to I export the table into Excel and reduce the table by sorting on the grid point ID and then sorting on the Distance table.  At that point, I can let the population accumulate and then I get rid of all records that exceed 50,000.  This has been a workable solution as a prototype (ie subset of census blocks).  However, I need a more automated solution for two reasons.  1)  I can't reduce the table as described above in Excel without chopping an extremely large dataset into several smaller tables.  And 2) My table is extremely large (I estimate it would be around 50,000,000 records) and I don't have the processing power to calculate a table of that size.

Any ideas for how I can accomplish this task?  Either the raster solution or the census block centroid solution would work.  All I need at the end of the process is a table with distance of a radius and a population sum for each grid point.

Outcomes