Where GridPin works and where it does not
A geocoder that answers everywhere is guessing somewhere. Here is where the country files are thin, and how an answer from such a place reads.
Know the limits Command line Retail, e-commerce Logistics, field work
What you have
11 country files: United States, Canada, Germany, France, Italy, Spain, Australia, Mexico, Netherlands, Brazil and Serbia. Each holds the addresses of one country; there is no file for the rest of the world. Sizes and sources: countries.
Steps
1. A Munich address on the Germany file, which has no Bavaria: the answer is a namesake far away, with a low score, after a warning on the terminal.
$ gridpin query germany.bin "Marienplatz 1, 80331 München" -k 1
{"lat":53.6289596,"lon":11.4107761,"precision":"house","score":0.42980862,"confidence":0.2,"street":"Marienplatz","housenumber":"1","commune":"Schwerin","postcode":"","flags":["street_exact","house_rep","ambiguous_far","dropped_suffix"],"weak":false,"match_level":"PointAddress","match_status":"M"}
gridpin: 5 places match; add the city to choose: Schwerin | Papenburg, Stadt | Bad Driburg | Nottuln | Naumburg (Saale), Stadt
2. A Miami Beach address: Florida is one of the states without address points, so the number is placed between known address ranges (interp, StreetAddress).
$ gridpin query usa.bin "1 Ocean Dr, Miami Beach, FL 33139" -k 1
{"lat":25.768327,"lon":-80.13332,"precision":"interp","score":-1.2127236,"confidence":0.4,"street":"Ocean Drive","housenumber":"1","commune":"Miami Beach","postcode":"33139","flags":["street_exact","commune_exact","pc_exact","range"],"weak":false,"match_level":"StreetAddress","match_status":"M"}
What you get
| Country | Known gap |
|---|---|
| Australia | the Open G-NAF licence does not allow compiling addresses for mail without checking each against a second source |
| France | places and shops are a separate file; Paris, Lyon and Marseille answer by arrondissement |
| Germany | Bavaria is not covered (15 of 16 Länder); Berlin answers by district |
| Mexico | the address layer was surveyed in 2009–2010; newer streets are missing, about half of the addresses carry a house number |
| United States | CO, FL, HI, MS, NH, NV and SC have no address points: numbers are placed between Census address ranges, tens to hundreds of metres off |
How often each country finds the right house, against independent truth: benchmark.
Why it works
Each file is built from one country's open address data, and the answer says how close it got: precision (house, interp, near, street, city) and match_level name the level, confidence scores it, and an empty answer is preferred to an invented one. Filter on those fields and the gaps above show up as low levels instead of wrong points.
Limits
- Addresses only: no landmarks or shops by name, except the France places file.
- A low score is not always marked
weak: the Munich answer above scores 0.2 and is not flagged, so filter onconfidenceand the town as well. - A country not in the list has no file; for a town-level answer elsewhere see towns of any country.
The answer fields: response format, confidence bands.