Overpass Turbo: How to do the equivalent of "SELECT distinct name FROM planet_osm_polygon WHERE (boundary = 'national_park');"

Question

In psql it's easy to do a query like "SELECT distinct name FROM planet_osm_polygon WHERE (boundary = 'national_park');" to return the names of national parks from a database. What's the equivalent in Overpass Turbo?

Various area selection methods exist such as "geocodeArea:Great Britain}}->.searchArea" followed by adding "(area.searchArea)" before the semicolon, but let's assume for now that a simple "({{bbox}})" query would work.

The link from taginfo, once I've commented out nodes and ways and added "({{bbox}})" gets me to https://overpass-turbo.eu/s/11DZ , but that's a visual query - I don't want the constituent ways, I don't want a map and I want a list of unique names (actually, to start with, just the number of items in the list).

There are some pages linked from https://wiki.openstreetmap.org/wiki/Overpass_turbo , but a search suggests there's nothing directly useful to me there.

Accepted Answer

1

This might not cover the DISTINCT bit, but change the top of your query from [out:json] to something like the example below?

[out:csv("name")][timeout:25];
// gather results
(
  // query part for: “protect_class=5”
  //node["protect_class"="5"]({{bbox}});
  //way["protect_class"="5"]({{bbox}});
  relation["protect_class"="5"]({{bbox}});
);
// print results
out body;
>;
out skel qt;

permanent link

answered 28 Dec '20, 18:32

EdLoach ♦
19.5k●16●156●280
accept rate: 22%

Actually it's good enough, because very few AONBs have separate outer polygons - of the ones in the rendering database, just the Forest of Bowland I think.

I'll work through the list of discrepancies to see if there are any obvious relation issues with the "missing" ones.

(28 Dec '20, 19:02) SomeoneElse ♦

Over at https://www.openstreetmap.org/user/SomeoneElse/diary/395232#comment48986 https://www.openstreetmap.org/user/mmd has suggested https://overpass-turbo.eu/s/11In .

(29 Dec '20, 20:27) SomeoneElse ♦

Answer 2

This is what I use:

// CSV list of National Parks 
[out:csv(::id, "name",::count; false; ",")];
area(id:3600058447,3600058437,3600058446); //EWS
rel(area)[boundary=protected_area][designation=national_park];
out;
out count;

Note the value change of the boundary tag from national_park to protected_area.

Also, ISO3166-1"="GB" would return data from Northern Island, if there were any, which is why I specify the ids for England, Wales & Scotland.

PS {{geocodeArea:Great Britain}}, for some reason, excludes GB's islands such as Sky, Isle of Wight & Sheppy; something I mean to bring up on Talk-GB.

Overpass Turbo: How to do the equivalent of "SELECT distinct name FROM planet_osm_polygon WHERE (boundary = 'national_park');"

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