This file is left here for reference. For discrepancies with stats results, the Protected Areas Programme now provides the country stats directly. Although the code is still present in the project, this is not called anymore.
The app renders three levels of stats: global, regional and country.
Stats are calculated, and then cached in their respective tables.
country_statistics for countries, and regional_statistics for
regions and global statistics.
bundle exec rake stats:calculate
There is a detailed, technical explanation available.
We have several protected areas that overlay each other. If we were calculating the sum of all their areas we would not get the real area protected. That is why we are dissolving the protected areas by country and type (marine/land).
In some countries we have a large number of protected areas and a very large detail on them. We were taking too long to calculate them and the country level results for simpflified geometries had no important errors. So, we have selected the countries which were taking more than an acceptable time and we have simplified their protected areas geometries in 0.005º so we can dissolve all PA's in an hour.
The only case where we intersect land protected areas with countries geometries is when we have protected areas that cross boundaries.
We are buffering the protected areas represented by points using their reported area. These buffers are then dissolved with the polygons so we can have a flat dataset. There is still an error in this one (Protected Areas aren't perfect circles) but this is the closest way of getting statistics for points.
We are excluding the following Protected Areas according to the PA team "Pre-processing of the WDPA dataset for coverage analyses" document:
- UNESCO-MAB Biosphere Reserves (UNESCO-MAB Réserve de Biosphère in French)
- Protected areas with 'Proposed' or 'Not Reported' status
We are intersecting the marine protected area with Exclusive Economic Zones and Territorial Seas so we can calculate the statistics for both zones.
We are considering that Russia and Turkey are in Asia to calculate stats. In the future we may change th DB structure to split the protected areas of these two countries and get more acurate values for Regional Statistics.
Geometries for countries are required for stats generation, and for generating shapefiles to be uploaded to CartoDB.
rake import:countries_geometries
The stats pages are dependent on a countries_geometries tables in
CartoDB for rendering country outlines on the map.
This is created using the geometries imported above. Export the countries geometries as a CartoDB compliant format (Shapefile, CSV, etc.) using ogr2ogr, shp2pgsql or even qgis, and upload to CartoDB.