Posts Tagged ‘ Indiana Breweries ’

Ranking the Indiana Breweries by Population

In my last post I used PostGIS to calculate the number of Hoosiers that live within 5 miles of an Indiana microbrewery.  Now I want to rank each brewery by population.  The total is going to be a little more than the 2.5 million-ish I came up in the last post due to the lucky duckies who live with 5 miles of more than one brewery.

Flat 12 of Indianapolis, with over 243,000 people within 5 miles of their location is our winner.  No big surprise, but the top 11, and 12 of the top 13 are all Indy breweries.

A few breweries, most notably Three Floyds in Munster are lower than they should be because I only used Indiana census data.  Three Floyds is only a half mile from the Indiana / Illinois border.  If I included Illinois data the nearby Chicago population would have pushed them up the list.

The full list and the SQL used to create it are below the jump.

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How many Hoosiers live with 5 miles of an Indiana brewery?

2,539,798.  Approximately.  I think.  Maybe.  Here’s what I did to get there.

First, the Census department has put together some nice pre-digested block layers, they include the total population for the blocks so you don’t have to compile that data yourself.

Second, create a 5 mile (acutally I used 8046.72 meters because my data in a UTM projection) buffer around my brewery points.  Shp2pgsql, use it to shove the buffers into a PostGIS database and call the layer buffer_5mile.  Fun!

Third, load the block data into QGIS and add a numeric field (I used totarea) to store the area of the blocks.  Use shp2pgsql to reproject the census data to match your buffers and load the results into PostGIS.  I called my layer block_pop.

Fourth, update that new area field with

UPDATE block_pop SET totarea = st_area(geom);

Fifth, to get an estimate of the population within the buffers use:

SELECT 
round(sum(c.pop10*(ST_Area(ST_Intersection(c.geom, b.the_geom))) / c.totarea)) 
FROM
(SELECT ST_Union(geom) as the_geom FROM buffer_5mile) as b, block_pop c
WHERE ST_Intersects(the_geom, c.geom);

Bam.  You done.