2c:null 2d:["$","title",null,{"children":"Calculate Road Intersection Density | GeoSurge | Observable"}] 32:[] 30:{"id":"3a0f5faede9675b5","slug":"calculate-road-density","title":"Calculate Road Intersection Density","thumbnail":"dfdb1286b7ce9a21e57652ceaa0b78c9e94c821fed9a64eff2a2c457e64ff704","access_level":"public","create_time":"$D2019-04-17T01:46:11.284Z","update_time":"$D2021-04-23T02:11:42.760Z","view_time":null,"first_public_time":"$D2019-04-18T15:13:02.838Z","has_unpublished_edits":null,"fork":false,"stars":0,"starred":false,"owner":{"type":"team","id":"3ed5fa3863496294","login":"geosurge","name":"GeoSurge","avatar_url":"https://avatars-next.observableusercontent.com/d6653d49bb2d126d5e686eeadc70f93ee30c3146a0d7e7912c62c771c5b9c43b","tier":"starter_2024"},"version":374,"publish_version":374,"role":null,"authored":false,"authors":[{"type":"individual","id":"41b7e572d952b912","login":"danieljdufour","name":"Daniel J. Dufour","avatar_url":"https://avatars-next.observableusercontent.com/6e4eba489aafe152091a2aac4028e0c05aae40bb2298dfa521e023b22f2f33b5","tier":null}],"members":[{"type":"team","id":"3ed5fa3863496294","login":"geosurge","name":"GeoSurge","avatar_url":"https://avatars-next.observableusercontent.com/d6653d49bb2d126d5e686eeadc70f93ee30c3146a0d7e7912c62c771c5b9c43b","tier":"starter_2024","role":"editor"}],"comments":[],"custom_thumbnail":false,"trashed":false,"lapsed":null,"subscribed":null,"forks":1,"collection":null,"type":"notebook","body":{"titling":"auto","title":"Calculate Road Intersection Density","cells":[{"id":0,"value":"md`# Calculate Road Intersection Density`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":5,"value":"md`\nThis notebook goes over how to calculate the density of roads in an area.\n1) Identify Intersections\n2) Get number of intersections per square grid cell\n3) Convert to GeoTIFF\n`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":25,"value":"shpjs = require('shpjs@3.4.3/dist/shp.js')","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":28,"value":"roads = fetch(\"https://s3.amazonaws.com/geoblaze/osm_roads_clip2.zip\")\n .then(response => response.arrayBuffer())\n .then(shpjs)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":159,"value":"viewGeoJSONLink = `http://geojson.io/#data=data:application/json,${encodeURIComponent(JSON.stringify(roads))}`;","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":168,"value":"html`View Roads in geojson.io`","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":34,"value":"intersections = {\n const points = [];\n const features = roads.features;\n const numLines = features.length;\n for (let a = 0; a < numLines; a++) {\n const line1 = features[a];\n for (let b = a + 1; b < numLines; b++) {\n const line2 = features[b];\n if (line1 != line2) {\n const intersections = turf.lineIntersect(line1, line2);\n if (intersections.features.length > 0) {\n intersections.features.forEach(intersection => {\n points.push(intersection.geometry.coordinates);\n })\n }\n }\n }\n }\n return points;\n}","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":59,"value":"turf = require('@turf/turf@5')","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":70,"value":"roadsBbox = turf.bbox(roads)","pinned":false,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":203,"value":"pixelSize = 0.005;","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":99,"value":"gridCells = {\n const [ minX, minY, maxX, maxY ] = roadsBbox;\n return turf.squareGrid([ minX-pixelSize, minY-pixelSize, maxX+pixelSize, maxY+pixelSize ], pixelSize, { units: 'degrees' });\n}","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":170,"value":"viewGridCellsLink = `http://geojson.io/#data=data:application/json,${encodeURIComponent(JSON.stringify(gridCells))}`;","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":172,"value":"html`View Grid Cells in geojson.io`","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":114,"value":"counts = gridCells.features.reduce((counts, gridCell) => {\n intersections.forEach(intersection => {\n const point = turf.point(intersection);\n if(turf.booleanContains(gridCell, point)) {\n const key = JSON.stringify(gridCell);\n if (counts[key]) counts[key]++;\n else counts[key] = 1;\n }\n });\n return counts;\n}, {});","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":178,"value":"cellsWithIntersections = Object.keys(counts).map(JSON.parse)","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":182,"value":"bboxCellsWithIntersections = turf.bbox(turf.featureCollection(gridCells.features))","pinned":true,"hidden":false,"mode":"ojs","author":"$undefined","summary":"$undefined","providerMetadata":"$undefined","attachments":"$undefined","output":"$undefined","database":"$undefined"},{"id":198,"value":"metadata = {\n const [minX, minY, maxX, maxY] = turf.bbox(gridCells);\n const height = Math.round((maxY - minY) / pixelSize); 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