Geocoding

[JohnTigue]

The geocoder takes names and turns them into [long,lat]. A reverse geocoder takes [long,lat]s and turns them into names (see #43).

The geocoder should evolve as follows

1. Completely naive: each lookup hits a remote geocoder
2. Caching: results are stored in memory, simply url encoded names as properties on an Object.
3. Pre-loaded cache: an external CSV file is loaded on startup and used to populate the cache. For EbolaMapper 2014Ebola, this will be loaded with Sierra Lione, Libaria, and Ginea data (ADM0, ADM1, ADM2).

This has the following benefits:

1. easy init coding
2. add on cache as a filter easily later.
3. performant once the cache is online.
4. still works with unknown names i.e. will still fall back to calling a geocoder API.

[JohnTigue]

Might as well tie this to Leaflet i.e. plug-in which returns a L.latLng. At a lower level perhaps there is a "class" which doesn't know about Leaflet. (probably not, as LatLng is pretty lightweight.

[JohnTigue]

For the pre-loaded cache, there should be a set of static files for all ADM0,1,2,3,4 data in the world. The non-overlapping model in ADM-land makes for a perfect mapping to a tree of files.

And how is naming done? And the index? each file is a CSV so there should be an index.csv? As well as an index.html, and index.xml? Certainly there is an index.js which is JSON with links to the GeoJSON files.

A dir will have an index and (possibly) sub-divisions i.e. sub-dirs.

There should be a way of saying "Give me all, say, AMD0 through ADM4 data for AMD0=foo. Or should there be? perhaps that is derived by the client?

And the same directory structure would handle loc-name to loc-name.geojson. The CSV links to the GeoJSON boundary files, which could be relative or remote URLs.

[JohnTigue]

Make sure not to reproduce any of this: http://leafletjs.com/plugins.html#geocoding-address-lookup

[JohnTigue]

Also consider the Mapbox API: https://www.mapbox.com/developers/api/geocoding/ https://www.mapbox.com/mapbox.js/example/v1.0.0/geocoding/

http://gis.stackexchange.com/questions/21890/does-leaflet-js-api-provide-a-geocoding-service/46799#46799

[JohnTigue]

Cheap caching mechanisms (go with the first answer first): http://stackoverflow.com/questions/368280/javascript-hashmap-equivalent

Note the last answer says: underscore.js or collections.js