EAlGIS Grahame Bowland

@angrygoathttp://ealgis.org/

Can anyone guess!what this map shows?

Public Transport Use! !

(did you spot the train lines?)

EAlGIS

• Build a reproducible database of geospatial information

• Interactive visualisation and analysis through a web interface

• Infrastructure for offline analysis, data-mashups…

Developed for…

Buzzwords!• Backend: Python / Flask / SQLAlchemy /

MapServer

• Database: PostGIS

• Frontend: jQuery, OpenLayers, Bootstrap

• Mozilla Personas for user authentication

• development: ‘vagrant up’

Reproducibility• Database built up by running ‘recipes’

• Built in loaders for Shapefile, KML, CSV attribute data

• Metadata! Database introspection & stored relationship data - attributes to geometries.

• Automatically reproject spatial data to map projection (eg. Google Mercator)

Attribute Calculations

Simple expression language, attributes looked up against current

geometry.

100 * (b7837 + b7840 + b7843 + b7846 + b7864 + b7894 + b7912 +

b7921 + b7924) / b7942

Generating this SQL!

SELECT sa1_2011_aust.geom_3857, sa1_2011_aust.gid, (100 * (b46_aust_sa1.b7837 + b46_aust_sa1.b7840 +

b46_aust_sa1.b7843 + b46_aust_sa1.b7846 + b46_aust_sa1.b7864 + b46_aust_sa1.b7894 + b46_aust_sa1.b7912 + b46_aust_sa1.b7921 +

b46_aust_sa1.b7924)) / CAST(b46_aust_sa1.b7942 AS FLOAT) + 0 AS q FROM sa1_2011_aust JOIN b46_aust_sa1

ON b46_aust_sa1.gid = sa1_2011_aust.gid JOIN b01_aust_sa1 ON b01_aust_sa1.gid = sa1_2011_aust.gid

WHERE b01_aust_sa1.b3 > 100 AND b46_aust_sa1.b7942 != 0) as subquery using unique gid using srid=3857

How that works

• Simple expression language parsed with “pyparsing”

• At parse time, look up attributes by name and resolve to SQLAlchemy column objects

• Emit into the parse tree

• Step back… and it works!

Mash All The Things!

• Electoral Analysis

• Power Grid utilisation

• Mash up data on different geometries

Demo!

Open Source

• Licensed under the GPL 3

• github.com/grahame/ealgis/

• github.com/grahame/ealgis-aus-census-2011/

Demo site

• http://census.ealgis.org/

• email grahame@angrygoats.net for access (public access coming soon!)

• help wanted :-)