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openstreetmapoverpass-api

How can I find a tag/way in another way/area with Overpass?

I want all industries in "Chemnitz" with a "hot_water_tank".

This query gives me all objects with tags "landuse"="industrial" and "man_made"="hot_water_tank". I need only the "landuse"="industrial" containing a "hot_water_tank".

area
  ["name"="Chemnitz"]->.a;        
out body qt;
(
  way
    (area.a)                   
    ["landuse"="industrial"];

    way(area.a)
   ["man_made"="hot_water_tank"];


);

out body qt;

>;

out skel qt;

i tried this 

area
  ["name"="Chemnitz"]->.a;        

(
  way
    (area.a)                   
    ["landuse"="industrial"]->.c;
    way(area.a)
   ["man_made"="hot_water_tank"]->.s;

  (.c; .s;)->.all;
  (.c; - .s;)->.I_without_T;
  (.s; - .c;)->.T_wihtout_I;
  ((.all; - .I_without_T;) - .T_without_I;);


);

out body qt;
>;
out skel qt;

Screenshots of the results:

here a industry with tanks, now i need only the industry with tanks the dark red point is the industry with hot_water_tanks, i need only a result with the industry

Solution

  • The key here was to use two little known statements from Overpass QL. First is_in gives us areas in which features are located, second we need to extract relations and/or ways from said areas using pivot.

    Here is a sample code:

    (area["name"="Chemnitz"]) -> .chemnitz; //Chemnitz

(
  way(area.chemnitz)["man_made"="hot_water_tank"];
  (._;>;)
)->.hotwatertank; // all tanks in Chemnitz

(.hotwatertank is_in;) -> .areas; // areas in which tanks are located

(
  way(pivot.areas)["landuse"="industrial"];
  relation(pivot.areas)["landuse"="industrial"];
)->._; // convert areas to ways and relations with "landuse"="industrial" pair

(._;._ >;); // get geometry
out body qt; //print