[GRASS-user] A few simple questions

Hamish hamish_b at yahoo.com
Sun Jan 24 04:05:16 EST 2010

Erik Lewis wrote:
> First let me apologize if this is the wrong venue to ask
> these questions.  If it is please kindly refer me
> somewhere else and I will leave you in peace.

It's the right place, but it strikes me that if you haven't already
you might want to check out QGIS as well, as a more beginner-friendly
GIS. (www.qgis.org)

> I'm a public librarian trying to bring a geographic aspect
> to our statistics.  Basically trying to answer
> questions of where our patrons live and what they check out
> so that I can plan facilities, collections, marketing, and a
> whole variety of other data to aid in the operation of a
> library system.  My experiments so far have involved
> using a geocoding website to encode my patrons address data
> with longitude and latitude.  While this looks
> impressive in Google Earth they are just data points. 
> What i'm really interested is encoding this data with US
> Census Tract and Block data to get actual comparisons of
> circulation against the various census data products. 
> So my questions are:
> 1)  Is there a way to encode my longitude and latitude
> data with US Census Tract and Block data so that I can get
> counts of my patrons at those layers of abstraction. 

Sure, TIGER data etc can be imported and you can overlay layers with
DB info and summary stats per feature, find which polygon a GPS point
is in, or line (road) that it is nearest to, etc.

TIGER data can be imported with v.in.ogr directly, or converted to
shapefiles with ogr2ogr and then imported. I'd note that it isn't the
simplest dataset to work with, but hopefully the documentation can lead
you through.

see  http://gdal.org/ogr/drv_tiger.html

(was there a GRASSnews article on importing it at some point??)

the OpenStreetMap data includes all the U.S. TIGER street info, you can
import it directly with v.in.ogr's OpenStreetMap XML support, or download
shapefiles of the OSM data from

> Ideally I want to load these values into a MySQL database
> for querying

not a problem, see  

> to make some thematic maps.

Thematic maps are not really GRASS's strong point, but they can be done.

> 2)  Based on if I can accomplish number 1 is GRASS the
> tool I should be spending my time with as opposed to Google
> Earth? 

Again, QGIS might be a happy medium between those two ends of the spectrum.
I'm not sure if it will let you work in MySQL though.

good luck,


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