30:Te1d,md`## Overpass QL To construct your own queries, there's extensive [Overpass QL reference documentation](https://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_QL). Here are some hints... ### overview * [Overpass Query Language (QL) overview](https://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_QL#Language_overview) -- openstreetmap.org * Overpass QL manipulates sets. * A set may contain any combination of nodes, ways, relations, and area elements. * A [node](https://wiki.openstreetmap.org/wiki/Node) is a single point defined by its lat, lon and id * A [way](https://wiki.openstreetmap.org/wiki/Way) is an ordered list of nodes (a linear feature) * A [relation](https://wiki.openstreetmap.org/wiki/Relation) is a group of elements -- an ordered list of one or more nodes, ways and relations * An [area](https://wiki.openstreetmap.org/wiki/Area) is a closed way * [Language structure](https://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_QL#Language_structure) * there are: (1) settings, (2) block statements, (3) standalone queries. ### settings * Overpass QL settings must be declared in the first uncommented statement * Not multiple statements * Declarations are enclosed in brackets [] * A colon : appears between the setting name and its value or values * The statement must be terminated with a semicolon ; * Ref: [Overpass QL settings](https://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_QL#Settings) -- openstreetmap.org * [maxsize](https://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_QL#Element_limit_.28maxsize:.29) * Maximum allowed memory in bytes. Default value is 536870912 (512 MB) * [out](https://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_QL#Output_Format_.28out:.29) * Output format (unrelated to the "out" statement) * For example: "json", "csv" (there are others) * [bbox](https://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_QL#Global_bounding_box_.28bbox.29) * Global bounding box (the "setting" is distinct from the bbox "query") * For example: [bbox:south, west, north, east] * [timeout](https://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_QL#timeout:) * Maximum allowed runtime for the query (seconds). Default is 180. * Large values may be rejected by the server. ### standalone queries * out; -- output contents of a set (almost always used) * [<; recurse up](https://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_QL#Recurse_up_.28.3C.29) takes an input set and produces a result set composed of: * all ways that have a node which appears in the input set; plus * all relations that have a node or way which appears in the input set; plus * all relations that have a way which appears in the result set * [>; recurse down](https://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_QL#Recurse_down_.28.3E.29) takes an input set and produces a result set composed of: * all nodes that are part of a way which appears in the input set; plus * all nodes and ways that are members of a relation which appears in the input set; plus * all nodes that are part of a way which appears in the result set * out body; -- print all information necessary to use the data (default) * for geolocated information (default is to print none)... * out geom; -- add a full geometry to each object * out skel; -- print minimum information for geometry * out center; -- adds only the center of the bounding box to ways and relations ### query-overpass [query-overpass](https://www.npmjs.com/package/query-overpass) returns GeoJSON from an API query written with Overpass QL `31:[] 2e:{"title":"OSM data viz","cells":[{"id":551,"value":"md`# OSM data viz\n\nThis notebook facilitates EDA of OSM data that comes from the Overpass API.\n\n* Reference: [Overpass API by example](https://wiki.openstreetmap.org/wiki/Overpass_API/Overpass_API_by_Example)`","pinned":false,"hidden":false,"mode":"ojs"},{"id":848,"value":"md`### Query the API...`","pinned":false,"hidden":false,"mode":"ojs"},{"id":444,"value":"viewof choice = Radio(Object.keys(queries), {value: 'maine_all', label: \"Choose a query:\"})","pinned":false,"hidden":false,"mode":"ojs"},{"id":349,"value":"viewof query = Textarea({\n label: \"OSM query\", \n rows: 7, \n placeholder: \"Type a query...\", submit: true})","pinned":false,"hidden":false,"mode":"ojs"},{"id":619,"value":"mutable report = html``","pinned":false,"hidden":false,"mode":"ojs"},{"id":323,"value":"container = html`

`","pinned":false,"hidden":false,"mode":"ojs"},{"id":784,"value":"md`### GeoJSON features`","pinned":false,"hidden":false,"mode":"ojs"},{"id":303,"value":"viewof rows = Table(geojson.features)","pinned":true,"hidden":false,"mode":"ojs"},{"id":787,"value":"md`### Feature properties\n\n...for GeoJSON features selected from the table (above)`","pinned":false,"hidden":false,"mode":"ojs"},{"id":666,"value":"viewof properties = Table(rows.map(d => d.properties))","pinned":true,"hidden":false,"mode":"ojs"},{"id":768,"value":"md`### unique properties.type`","pinned":false,"hidden":false,"mode":"ojs"},{"id":737,"value":"[...new Set(rows.map(d => d.properties.type))] // Unique \"properties.type\"s","pinned":true,"hidden":false,"mode":"ojs"},{"id":743,"value":"rows.filter(d => d.properties.type == 'node')","pinned":true,"hidden":false,"mode":"ojs"},{"id":772,"value":"md`### unique highways\n\nIf a \"highway\" is a feature with a non-null properties.tags.highway, and the value of properties.tags.highway is the \"highway type\", then the next cell is an array of the ${highway_types.length} unique highway types.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":765,"value":"highway_types = [...new Set(highways.map(d => d.highway))]","pinned":true,"hidden":false,"mode":"ojs"},{"id":796,"value":"md`### highway tags\n\nThese are the properties.tags for \"highways\" (as defined above).`","pinned":false,"hidden":false,"mode":"ojs"},{"id":694,"value":"viewof highways = Table(rows.map(d => d.properties.tags).filter(d => d.highway))","pinned":true,"hidden":false,"mode":"ojs"},{"id":816,"value":"md`### tags of features that are not highways\n\nThere are ${highways.length} highways out of ${geojson.features.length} total features;\n${not_highway.length} are not highways.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":759,"value":"viewof not_highway = Table(rows.map(d => d.properties.tags).filter(d => !(d.highway)))","pinned":true,"hidden":false,"mode":"ojs"},{"id":567,"value":"md`## map stuff`","pinned":false,"hidden":false,"mode":"ojs"},{"id":322,"value":"map = {\n const map = L.map(container).setView([39.74739, -105], 13);\n \n\tL.tileLayer('https://stamen-tiles-{s}.a.ssl.fastly.net/terrain/{z}/{x}/{y}{r}.png', {\n\t\tmaxZoom: 18,\n\t\tattribution: 'Map tiles by Stamen Design, under CC BY 3.0. Data by OpenStreetMap, under CC BY SA',\n\t\ttileSize: 512,\n\t\tzoomOffset: -1\n\t}).addTo(map);\n \n invalidation.then(() => map.remove()); // Clean up when re-running this cell\n return map;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":387,"value":"layer = {\n const style = {\n \"color\": \"crimson\",\n \"weight\": 5,\n \"opacity\": 0.65\n };\n \n function onEachFeature(feature, layer) {\n if (feature.properties && feature.properties.tags && feature.properties.tags.name) {\n layer.bindPopup(feature.properties.tags.name);\n } else {\n layer.bindPopup(feature.properties.type + \" id: \" + feature.properties.id)\n }\n }\n \n const layer = L.geoJSON([geojson], {\n\n style: style,\n onEachFeature: onEachFeature,\n\n\t\tpointToLayer: function (feature, latlng) {\n\t\t\treturn L.circleMarker(latlng, {\n\t\t\t\tradius: 4,\n\t\t\t\tfillColor: \"blue\",\n stroke: \"black\",\n\t\t\t\tcolor: \"#000\",\n\t\t\t\tweight: 1,\n\t\t\t\topacity: 1,\n\t\t\t\tfillOpacity: 0.5\n\t\t\t});\n\t\t}\n\t}).addTo(map);\n \n map.fitBounds(layer.getBounds(), {padding: [20, 20]});\n \n invalidation.then(() => map.removeLayer(layer));\n return layer\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":240,"value":"$30","pinned":false,"hidden":false,"mode":"ojs"},{"id":0,"value":"md`### References and other demos\n\n* [Overpass Boundary Queries](https://observablehq.com/@nzzeditotech/overpass-boundary-queries) uses [query-overpass](https://github.com/perliedman/query-overpass) -- observable\n* [Overpass API](https://observablehq.com/@rjsheperd/overpass-api) uses [encodeURIComponent()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/encodeURIComponent) -- observable\n* [Overpass turbo](https://wiki.openstreetmap.org/wiki/Overpass_turbo) (OSM data-mining tool) -- openstreetmap.org\n * Go to http://overpass-turbo.eu and try this...\n rel[\"ISO3166-2\"~\"^FR\"]\n [admin_level=4]\n [type=boundary]\n [boundary=administrative];\n out geom;`","pinned":false,"hidden":false,"mode":"ojs"},{"id":538,"value":"md`## Get the data\n\nQuery the API...`","pinned":false,"hidden":false,"mode":"ojs"},{"id":300,"value":"geojson = queryOverpassGeoJSON(query)","pinned":true,"hidden":false,"mode":"ojs"},{"id":288,"value":"function queryOverpassGeoJSON(query) {\n mutable report = md`Please wait...`;\n return new Promise((resolve, reject) => {\n queryOverpass(query, (error, data) => {\n if (error) {\n mutable report = error;\n reject(error);\n } else {\n mutable report = md`${data.features.length} features returned.`;\n resolve(data);\n }\n });\n });\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":830,"value":"md`The following is a collection of pre-packaged queries.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":436,"value":"queries = ({\n switzerland: `[out:json];\n relation\n [boundary=administrative]\n [\"ISO3166-2\"~\"^CH\"];\n\n out; >; out skel;`,\n dc: `[out:json];\n node(38.9072, -77.0369, 38.9102, -77.0339);\n out;`,\n dc_all: `[out:json];\n\n (\n node(38.9072, -77.0369, 38.9102, -77.0339);\n <;\n ); out meta;`,\n dc_extended: `[out:json];\n\n (\n node(38.9072, -77.0369, 38.9102, -77.0339);\n <;\n ); out; >; out skel;`,\n oregon: `[out:json][timeout:25][bbox:45.4797,-122.7035, 45.5625,-122.6182];\n node[\"amenity\"=\"bicycle_parking\"];\n out; >; out geom;`,\n maine_all: `[out:json];\n\n (\n node(43.64, -70.25, 43.66, -70.23);\n <;\n ); out meta;`\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":911,"value":"md`Portland, ME: 43.6591° N, 70.2568° W`","pinned":false,"hidden":false,"mode":"ojs"},{"id":480,"value":"{ \n viewof query.value = choice ? queries[choice] : null;\n viewof query.dispatchEvent(new Event('input'))\n \n return md`This cell links the Radio button and the TextArea submit button.`\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":184,"value":"md`## Appendix`","pinned":false,"hidden":false,"mode":"ojs"},{"id":297,"value":"queryOverpass = require('https://bundle.run/query-overpass@1.5.5')","pinned":false,"hidden":false,"mode":"ojs"},{"id":280,"value":"import {Textarea, Table, Radio} from \"@observablehq/inputs\"","pinned":false,"hidden":false,"mode":"ojs"},{"id":6,"value":"d3 = require(\"d3@5\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":329,"value":"L = {\n const L = await require(\"leaflet@1/dist/leaflet.js\");\n if (!L._style) {\n const href = await require.resolve(\"leaflet@1/dist/leaflet.css\");\n document.head.appendChild(L._style = html``);\n }\n return L;\n}","pinned":false,"hidden":false,"mode":"ojs"}],"files":"$W31","stdlib":"1","titling":"auto"}