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TopoJSON and GeoVisualization
sampleFeatureCollection = topojson.feature(
sampleTopology,
sampleTopology.objects["two-squares"]
)
Object.keys(sampleTopology.objects).map(key =>
topojson.feature(sampleTopology, sampleTopology.objects[key])
)
topojson.merge(sampleTopology, Object.values(sampleTopology.objects))
sampleTopology = JSON.parse(sampleTopoJsonData)
sampleTopoJsonData = `
{
"type":"Topology",
"transform":{
"scale": [1,1],
"translate": [0,0]
},
"objects":{
"two-squares":{
"type": "GeometryCollection",
"geometries":[
{"type": "Polygon", "arcs":[[0,1]],"properties": {"name": "Left_Polygon" }},
{"type": "Polygon", "arcs":[[2,-1]],"properties": {"name": "Right_Polygon" }}
]
},
"one-line": {
"type":"GeometryCollection",
"geometries":[
{"type": "LineString", "arcs": [3],"properties":{"name":"Under_LineString"}}
]
},
"two-places":{
"type":"GeometryCollection",
"geometries":[
{"type":"Point","coordinates":[0,0],"properties":{"name":"Origine_Point"}},
{"type":"Point","coordinates":[0,-1],"properties":{"name":"Under_Point"}}
]
}
},
"arcs": [
[[1,2],[0,-2]],
[[1,0],[-1,0],[0,2],[1,0]],
[[1,2],[1,0],[0,-2],[-1,0]],
[[0,-1],[2,0]]
]
}`
usCounties = topojson.feature(usTopology, usTopology.objects.counties).features
usStates = topojson.feature(
usTopology,
usTopology.objects.states
).features
usLand = topojson.feature(usTopology, usTopology.objects.land)
usTopology = d3.json(
"https://gist.githubusercontent.com/mbostock/4090846/raw/d534aba169207548a8a3d670c9c2cc719ff05c47/us.json"
)
{
const [svgNode, svg] = getSVG(width, height);
svg
.append("path")
.attr("d", geopathGenerator(stateExteriors))
.style("stroke", "black")
.style("stroke-width", 1)
.style("fill", "none");
svg
.append("path")
.attr("d", geopathGenerator(stateInteriors))
.style("stroke", "green")
.style("stroke-width", 1)
.style("fill", "none");
return svgNode;
}
stateInteriors = topojson.mesh(
usTopology,
usTopology.objects.states,
(a, b) => a !== b
)
stateByUSPS = Object.fromEntries(
stateNamesAndCodes.map(d => [
d[" stusps"].trim(),
{ ID: d[" st"], name: d.stname }
])
)
usStates
countyNeighbors = topojson.neighbors(usTopology.objects.counties.geometries)
stateColorIndex = {
const index = Array(usStates.length);
stateNeighbors.forEach(
(A, i) => (index[i] = (d3.max(A, j => index[j]) + 1) | 0)
);
return index;
}
countyColorIndex = {
const index = Array(usCounties.length);
countyNeighbors.forEach(
(A, i) => (index[i] = (d3.max(A, j => index[j]) + 1) | 0)
);
return index;
}
getSVG = (width, height, margin = 0, outline = false) => {
const svgElement = DOM.svg(width, height);
let svg = d3.select(svgElement);
if (outline)
svg
.append("rect")
.attr("width", width)
.attr("height", height)
.style("stroke", "black")
.style("fill", "none");
if (margin)
svg = svg.append("g").attr("transform", `translate(${margin},${margin})`);
return [svgElement, svg];
}
usStatesSimplifiedTopology = {
let us_simplified = topojson.presimplify(usTopology);
let min_weight = topojson.quantile(us_simplified, weight);
us_simplified = topojson.simplify(us_simplified, min_weight);
return us_simplified;
}
usStatesSimplified = topojson.feature(
usStatesSimplifiedTopology,
usStatesSimplifiedTopology.objects.states
).features
viewof weight = slider({ min: 0, max: .1, step: 0.0001, description: "" })
md`#### US states by Region
See: https://en.wikipedia.org/wiki/List_of_regions_of_the_United_States
`
{
const [svgNode, svg] = getSVG(width, height, 0, true);
const divisions = svg
.selectAll("g")
.data(usDivisionFeatures)
.join("g");
divisions
.append("path")
.attr("d", geopathGenerator)
.style("fill", (d, i) => d3.schemeCategory10[i])
.append("title")
.text((d, i) => usDivisions[i]);
return svgNode;
}
usRegionFeatures = Array.from(usStatesGroupedByRegion.keys()).map(region =>
topojson.merge(
usTopology,
usTopology.objects.states.geometries.filter(d => inRegion(region, d.id))
)
)
usDivisionFeatures = Array.from(usStatesGroupedByDivision.keys()).map(division =>
topojson.merge(
usTopology,
usTopology.objects.states.geometries.filter(d => inDivision(division, d.id))
)
)
inRegion = (region, id) => {
const stateUSPS = stateNameByCode.get(id);
if (stateUSPS) {
return usRegionByState[stateUSPS[0][" stusps"].trim()] === region;
} else return false;
}
inDivision = (div, id) => {
const stateUSPS = stateNameByCode.get(id);
if (stateUSPS) {
return usRegionByDivision[stateUSPS[0][" stusps"].trim()] === div;
} else return false;
}
usRegions = Array.from(usStatesGroupedByRegion.keys())
usStatesGroupedByRegion = d3.group(usStateRegions, d=>d.Region)
usDivisions = Array.from(usStatesGroupedByDivision.keys())
usStatesGroupedByDivision = d3.group(usStateRegions, d => d.Division)
usRegionByState = Object.fromEntries(
usStateRegions.map(d => [d["State Code"], d["Region"]])
)
usRegionByDivision = Object.fromEntries(
usStateRegions.map(d => [d["State Code"], d["Division"]])
)
usStateRegions = (await FileAttachment("states.csv")).csv()
height = 500
projection = d3.geoAlbersUsa().fitSize([width, height], usLand);
geopathGenerator = d3.geoPath().projection(projection)
md`### External Libraries and Imports`
import { slider } from "@jashkenas/inputs"
import { soFetch } from '@alecglassford/so-fetch'
topojson = require("topojson")
d3 = require("d3@6")
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