The Input files

For the computer to do redistricting, the computer must receive certain data. Sandboxwalls used three data files as input. The first file contained the census block data. The second file contained the borders of the State as a polygon. The third file contained the information on what census blocks were immediately adjacent to any given census block.

The first file was the bloated census data file from the Census Bureau. The only information needed by Sandboxwalls from that file was the census block data. The data needed for each census block was only the following: the latitude, the longitude, the county, the city, and of course the population. Also included was the census tract and census group, but those weren’t really needed, so Sandboxwalls won’t use them in the future. I am going to add the possibility of neighborhood or district or parish or ward or whatever else you would call the subdivision of a city. As I suggested in my last blog, the use of an extractor program will considerably reduce the size of a file used to replace the first file.

The second file was a database file from the Internet that gave the borders of the State. Digital decay takes its toll, and I can no longer find such files. Back then, I had considered the possibility of using the latitude and longitude of the census blocks to re-create a State border. One reason I didn’t do that was the existence of the database file for each State. Also, the actual State border would inevitably be different from the result achieved by an algorithm that would re-create the State border from the census blocks. I am now writing such an algorithm. At least that will make the second file superfluous. The algorithm will be included in Sandboxwalls.

The third file on adjacent blocks was made from various files available from the Census Bureau. Hopefully, some day others will become interested in creating such a file on adjacent blocks. The format I suggested in my blog of October 2011 still seems reasonable, but creating such a file hasn’t gotten any easier. It also hasn’t attracted any interest since then.

Meanwhile, there are other problems to consider, such as saving water during this drought here in Silicon Valley


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