At the invitation of Eva Adler and Norman Shamas I had the pleasure of giving a workshop on CartoDB's real-time mapping capabilities for the TechChange class [Mapping for Social Good]. Eva Adler's course covers an impressive array of material on web mapping related to global development work.
I gave a short workshop introducing the real-time mapping available through CartoDB's sync tables to create a map that updates hourly with earthquake data pulled from the United States Geological Survey servers. Using the spatial analysis functionality of PostGIS I showed how to join the dataset of earthquakes (which comes as latitude/longitude points) with the districts of Nepal (which are polygons) producing a map from an on-the-fly calculation. The result visualizes the largest earthquake from the USGS dataset that intersects with a district in Nepal. This is the SQL that I used (names changed for readability):
SELECT n.district_name n.the_geom_webmercator max(e.magnitude) As max_magnitude n.cartodb_id FROM nepal_districts AS n JOIN all_month_10 As e ON ST_Intersects(n.the_geom e.the_geom) GROUP BY n.district_name n.the_geom_webmercator n.cartodb_id ##_END_REPLACE_ME_PRE_##
All you need to do is paste your custom SQL into the SQL tray in the CartoDB Editor when you're creating your visualization and it will run against your tables to produce the up-to-date map everytime someone looks at it. It's pretty magical in my opinion! If you want to learn the basics of SQL checkout our course on SQL and PostGIS in our Map Academy.
Want to get this crash course on mapping real-time data that is beyond just a basic dataset? Take a look at the [write up] and watch the video.
[Mapping for Social Good] will be taught again starting October 26 so don't fret about missing Eva's course this time around. If you want to get trained in other next-generation skills check out TechChange's awesome offerings.
Happy data Mapping!