Hello.
When you look up “Graix, France” and toggle the address near “La Chaperie” or “Valsoiron”, the address is the name of a housing estate that’s 10km away: “Lotissement Le Parc, La Barraque, Bourg-Argental”. I think it’s related to some property of the road D2 which is inbetween, but I couldn’t find how to remove or at least change it. I could use a little help. 
Regards, Orikrin
If I do that search: http://www.openstreetmap.org/search?query=Graix%2C%20France#map=13/45.3606/4.5545 neither “La Chaperie” nor “Valsoiron” appear in the results, for either of Nominatim or Geonames.
I’m not sure exactly what you mean by toggle the address, but I’m guessing you mean click on the search results
Can you please provide a way or node URL for one of the problem objects. Are you referring to http://www.openstreetmap.org/node/4060983355 and http://www.openstreetmap.org/node/4060983353 ?
These are both isolated dwellings. The enclosing places query times out, but I assume that Lotissement Le Parc ( http://www.openstreetmap.org/node/4908117939 ) is the nearest possible containing place currently mapped.
Generally the best solution is to map the containing districts as areas, rather than nodes, but that does depend on being able to find the boundary without breaching copyright.
The other solution is to use is_in tags ( http://wiki.openstreetmap.org/wiki/Key:is_in ) or is_in:xxxxx tags.
Please note, however, that none of this will give the postal address. For that, you must put a suitable set of addr:xxxx tags on the building in question.
I looked at the roads near the place you mentioned, and none of them have addr tags. However, you may well be right that Nominatim will associate the road with a containing area, in which case you need to split the road at the boundaries.
When you right-click on any close area to La Chaperie, and then click on “show the address”, it shows that distant housing estate. I would merely like that to disappear because it’s completely irrelevant. The area is this one :
http://www.openstreetmap.org/search?query=Graix%2C%20France#map=16/45.3437/4.5660 but the problem exists all along the D2 from there to Bourg-Argental.
As I said, you need to split the road, at the relevant boundaries. It probably is identifying the road as the thing with the address, and as it is a single way, the whole way will have the same, implied, is_in attributes.
Take a look at http://nominatim.openstreetmap.org/details.php?place_id=77076094
This is obtained after pressing “details” on http://nominatim.openstreetmap.org/search.php?q=45.34042%2C4.56715&polygon_geojson=1&viewbox=
It shows that “Lotissement Le Parc” is marked as a neighborhood and it’s a node. Since there are no other neighborhood nearby Nominatim just assumes that that is the neighborhood to which the D2 belongs.
I doubt that splitting the way will help. I know that some people do not like to have a boundary relation for a neighborhood, as the boundaries are vague, it’s the only way to stop Nominatim from returning the wrong neighborhood. Of course this can be seen a some form of “mapping for the geocoder”.
Alright ! So, thank you escada, it was indeed because the neighbourhood was a point that the road was considered as belonging to it. I turned the point to a polygon and my initial problem is now fixed. \o/
Nevertheless I have another one. As shown in the following picture, there is a fictive line (the red one I drew roughly) on the north side of which the address is “…Graix…”, and on the south side of which it’s “…Bourg-Argental…”. I couldn’t find why, because there is no boundary of any type there. How can I tell the map that La Chaperie belongs to Graix ? Besides La Chaperie is within the range of the commune (the territorial district of Graix) : http://www.openstreetmap.org/relation/907288#map=14/45.3606/4.5545
Relation http://www.openstreetmap.org/relation/2505709#map=12/45.3083/4.5495 shows as disused boundary, end 2015 ??
But the address is related to Graix on the north of the line I drew, and that boundary is way up north. I don’t see how that could be our problem.
It seems like the “show address” on osm.org does not work properly.
If you search for La Chaperie in the search box, or via Nominatim, it belongs to Graix.
http://nominatim.openstreetmap.org/details.php?place_id=52432000, also the relation of Graix stretches out below La Chaperie: http://www.openstreetmap.org/relation/907288#map=15/45.3495/4.5698
But the show address, picks a road (D2 / D8) depending on where you click. Depending on the road, you get Bourg/Graix.
Seems like “Show Address” tries to find the nearest road with a name and then work from there.
I think show address is basically doing a Nominatim search on the raw latitude and longitude. You get the same result if you do that directly in the search box.
My guess would be that Nominatim pre-computes is_in relations for all OSM ways and named nodes, but can’t do so for the infinite number of possible coordinate pairs, so uses the information from the nearest suitable object, rather than doing an expensive, first principle search. If it is doing that, splitting the way is likely to help, unless it tries to consolidate the way before assigning it to regions.