2e:null 2f:["$","title",null,{"children":"Client-Side Geospatial Functions | Emu Analytics | Observable"}] 34:[] 32:{"id":"f26d6bc1bad2a372","slug":"client-side-geospatial-functions","title":"Client-Side Geospatial Functions","thumbnail":"b1780c5db813fe2866b043ee09dc9b49bd9944ef5dd91c4f213f986a7f2618fc","access_level":"public","create_time":"$D2021-01-10T11:55:23.581Z","update_time":"$D2023-12-11T16:46:58.466Z","view_time":null,"first_public_time":"$D2021-02-09T11:13:15.540Z","has_unpublished_edits":null,"fork":true,"stars":0,"starred":false,"owner":{"type":"team","id":"374dcc63ddd06df5","login":"emuanalytics","name":"Emu Analytics","avatar_url":"https://avatars-next.observableusercontent.com/be971faab0532b04c1173a4e3af506aaf7228fe01f5d68db47f0459eff95d96d","tier":"pro"},"version":125,"publish_version":125,"role":null,"authored":false,"authors":[{"type":"individual","id":"bdf516c467dde4e8","login":"robinsummerhill","name":"Robin Summerhill","avatar_url":"https://avatars-next.observableusercontent.com/a9ff6855f02eecd3b45d5c8360553ae7dde7a80f4b79d56742af72792b79ad58","tier":null}],"members":[{"type":"team","id":"374dcc63ddd06df5","login":"emuanalytics","name":"Emu Analytics","avatar_url":"https://avatars-next.observableusercontent.com/be971faab0532b04c1173a4e3af506aaf7228fe01f5d68db47f0459eff95d96d","tier":"pro","role":"editor"},{"type":"individual","id":"bdf516c467dde4e8","login":"robinsummerhill","name":"Robin Summerhill","avatar_url":"https://avatars-next.observableusercontent.com/a9ff6855f02eecd3b45d5c8360553ae7dde7a80f4b79d56742af72792b79ad58","tier":null,"role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":4,"collection":{"id":"a648749434bc8b5a","slug":"flo-w-examples","title":"Flo.w Examples","owner":{"id":"374dcc63ddd06df5","login":"emuanalytics","name":"Emu Analytics"}},"type":"notebook","body":{"title":"Client-Side Geospatial Functions","cells":[{"id":0,"value":"md`\n\n# Client-Side Geospatial Functions\n\nThis example illustrates using the [Turf.js](https://turfjs.org) geospatial library to perform client-side geospatial operations.\n\nAir quality point data is loaded as a GeoJSON feature collection using A Flo.w RDF reactive query. The query results are transformed form points to polygons using the Turf.buffer() function. The polygons are displayed using a 3D extruded fill layer.\n`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":43,"value":"map1 = html`\n\n\n\n \n \n \n\n \n \n fill-extrusion-color: @no2 ? from-palette('OrRd', @no2, 0, 100) : gray;\n fill-extrusion-height: @no2 * 20;\n \n\n \n

\n \n \n

\n\n\n`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":85,"value":"// Set map pitch\ncontext.maps.getMap('map1').then(map => map.mapboxMap.setPitch(60))","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":54,"value":"// Use Turf.buffer to calculate polygons from points\ncontext.state.compute('polygons', state =>\n turf.buffer(state.queries.airquality.results, 300, { units: 'metres' })\n)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":48,"value":"// Register query to retrieve airquality point data\ncontext.state.registerQuery('queries.airquality', state => ({\n datasetId: 'airquality',\n format: 'geojson'\n}))","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":4,"value":"md`## Appendix `","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":9,"value":"apiKey = 'b6b77cc4-904a-46d1-aa0f-3bf3848ce4c7'","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":11,"value":"import {\n initializeFlow,\n datasetTable,\n tileSourceTable,\n datasetSource,\n datasetAttributes\n} from '@emuanalytics/flow-helper-library'","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":14,"value":"context = {\n const context = await initializeFlow(apiKey, '1.1.7');\n return context;\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":120,"value":"turf = require(\"@turf/turf\")","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"},{"id":46,"value":"html`\n\n`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","output":"$undefined","database":"$undefined"}],"files":"$W34","stdlib":"1","titling":"auto"}} 33:"$32:body"