I'm a professor of mathematics at the University of North Carolina Asheville. I've also done a fair amount of consulting work over the years focusing on scientific and data visualization.
I'm happy to be part of the first Observable Ambassador's cohort.
NC Congressional DistrictsTrivariate choropleth for racial composition in the USRacial distribution in NCWNC ZoomNC CountiesTriangulated Canadian Provinces (separate)Triangulated NC CountiesAn X3D GlobeCanadian Elections 3DWNC SurroundElectoral Results TilegramThe new Electoral CollegeElectoral MapGPX rides with Leaflet and OSMOld encoded polyline rides with LeafletGPX rides with Maplibre and MaptilerBuncombe county votingThe NC Congressional redistricting battleHexapolis 538Zillow Home PricesSetting up HexapolisCOVID curvesThirty day Map Challenge - Day 1Simple grid cartogram2020 Census Apportionment TilegramMass shootings in the USHBCUsNC State Legislative Elections 2022Hierarchical Structure of the US RegionsIndigenous territories of the SoutheastD3.force to desired positionPopulation Choropleth for the Contiguous US StatesPlotting a few points on a mapMutliple bubble maps for CSV dataWorld population bubble mapReproductive rights and ... ??Gerrymandering Hexapolis by handVisualizations of gun ownership dataIncome inequality in North Carolina
3D Choropleth for NC County Populations
Also listed in…
X3Dom
function* make_choropleth3D() {
let width = 900;
let height = 400;
let container = d3
.create('div')
.style('width', width.toString() + 'px')
.style('height', height.toString() + 'px');
let scene = container
.append('x3d')
.attr('width', width.toString() + 'px')
.attr('height', height.toString() + 'px')
.append('scene');
scene
.append("viewpoint")
.attr("centerOfRotation", "996 64700 0")
.attr("position", "-3065.65419 56723.69512 5351.94013")
.attr("orientation", "0.97625 -0.13632 -0.16837 1.00157");
let T = scene.append('transform');
['VD', 'VP', 'HD', 'HP'].forEach(function(t) {
let G = T.append('group').attr('id', t);
triangulated_counties.forEach(function(c) {
G.append(() => county3D(c, t));
});
});
scene
.select('#VP')
.selectAll('material')
.attr('transparency', 0);
T.attr('scale', '1,1,0.01');
Promises.delay(500).then(function() {
T.transition()
.duration(1000)
.attr('scale', '1,1,1');
});
yield container.node();
x3dom.reload();
}
// Determine height based type
// VD means volume proprtional to density
// VP means volume proportional to population
// HD means height proporitonal to density
// HP means height proporitonal to population
function height(county, type) {
let pop = county.properties.pop;
let A = county.properties.ALAND + county.properties.AWATER;
if (type == 'VD') {
return (3 * 10 ** 15 * pop) / (A * A);
} else if (type == 'VP' || type == 'HD') {
return (3 * 10 ** 6 * pop) / A;
} else if (type == 'HP') {
return (2 * pop) / 10 ** 3;
} else {
return 0;
}
}
function county3D(county, type) {
let pt_string_top = '';
let pt_string_bot = '';
let h = height(county, type);
county.pts.map(function(pt) {
pt_string_top = `${pt_string_top}${pt[0]} ${pt[1]} ${h}, `;
pt_string_bot = `${pt_string_bot}${pt[0]} ${pt[1]} 0, `;
});
let pt_string = pt_string_top + pt_string_bot;
let top_coord_string = '';
county.triangles.map(function(t) {
top_coord_string = `${top_coord_string}${t[0]} ${t[1]} ${t[2]} -1 `;
});
let n = county.pts.length;
let side_coord_string = '';
county.segments.map(function(s) {
side_coord_string = `${side_coord_string}${s[0]} ${s[1]} ${s[1] +
n} ${s[0] + n} -1 `;
});
let coord_string = `${top_coord_string} ${side_coord_string}`;
let color;
if (type == 'HD' || type == 'VD') {
let density =
county.properties.pop /
(county.properties.ALAND + county.properties.AWATER);
color = d3.interpolateBlues((density / max_density) ** 0.2);
} else if (type == 'HP' || type == 'VP') {
color = d3.interpolateBlues((county.properties.pop / max_pop) ** 0.2);
}
let g = d3.create('group');
let shape = g.append('shape');
let appearance = shape.append('appearance');
appearance
.append('material')
.attr('transparency', 1)
.attr('diffuseColor', color);
let ifs = shape
.append('IndexedFaceSet')
.attr('solid', 'false')
.attr('coordIndex', coord_string);
ifs.append('coordinate').attr('point', pt_string);
return g.node();
}
max_density = d3.max(
triangulated_counties.map(
c => c.properties.pop / (c.properties.ALAND + c.properties.AWATER)
)
)
max_pop = d3.max(triangulated_counties.map(c => c.properties.pop))
triangulated_counties = FileAttachment('nc_triangulated3.json').json()
d3 = require('d3@5')
x3dom = require('x3dom').catch(() => window['x3dom'])
style = html`<style>
canvas {
outline: none;
}
</style>`
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