md`# Choropleth Mapping [GEOG 3540]
Count of Providers in Iowa Counties, Source: [CMS Doctors and Clinicians 2023]`
d3 = require("d3@5")
import {legend} from "@d3/color-legend"
simple = require("simple-statistics@7.0.7/dist/simple-statistics.min.js")
format = d => `${d}%`
topojson = require("topojson-client@3")
iowa = FileAttachment("IA_zip5.json").json()
zips_features = topojson.feature(iowa, iowa.objects.IA_zip5)
csv_data = d3.csvParse(await FileAttachment("prov_count2023.csv").text(),({zip5, count}) => [+zip5, [+count]])
data = Object.assign(new Map(csv_data), {title: "Proportion of Providers"})
count_prov = Array.from(csv_data.values(), d => d[1][0])
YlGnBu = [d3.color("#ffffcc"), d3.color("#a1dab4"), d3.color("#41b6c4"), d3.color("#2c7fb8"),d3.color("#253494")]
naturalbreaks5 = simple.ckmeans((count_prov), YlGnBu.length).map(v => v.pop())
nancolor = d3.color("grey")
nullcolorforlegend = d3.scaleOrdinal()
.domain([NaN])
.range([nancolor])
naturalbreaks = d3.scaleThreshold()
.domain(naturalbreaks5)
.range(YlGnBu)
linear = d3.scaleLinear()
.domain(d3.extent(Array.from(count_prov)))
.range(YlGnBu)
quantile = d3.scaleQuantile()
.domain(d3.extent(Array.from(count_prov)))
.range(YlGnBu)
//more information on sequential scales: https://observablehq.com/@d3/sequential-scales
// color = d3.scaleSequentialQuantile([...data.values()], d3.interpolateBlues)
//color = d3.scaleQuantile()
// .domain(count_prov)
//.range(YlGnBu)
// color = d3.scaleThreshold()
// .domain(naturalbreaks)
// .range(YlGnBu)
width = 975
height = 610
margin = 100
//Rotate the map sets the longitude of origin for our UTM Zone 15N projection.
projection = d3.geoTransverseMercator().rotate([94,0]).fitExtent([[80, 80], [width, height]], zips_features);
//d3 reference for projections: https://github.com/d3/d3-geo/blob/master/README.md
//use the following url for specific projection settings: https://github.com/veltman/d3-stateplane
//Use this code to set up the map projection (if different than geographic projection)
//projection = d3.geoAlbers().fitExtent([[margin, margin], [width - margin, height - margin]], counties)
//projection = d3.geoMercator().fitExtent([[margin, margin], [width - margin, height - margin]], counties)
//Using a path generator to project geometry onto the map
path = d3.geoPath().projection(projection);
choropleth = {
const svg = d3.create("svg")
.attr("viewBox", [0, 0, width, height]);
svg.append("g")
.attr("transform", "translate(360,20)")
.append(() =>
legend({
color: quantile,
title: data.title,
width: 260,
tickFormat: ".2f"
})
);
svg.append("g")
.attr("transform", "translate(700,20)")
.append(() =>
legend({
color: nullcolorforlegend,
title: "No Data",
width: 50,
tickFormat: ".1f"
})
);
svg.append("g")
.selectAll("path")
.data(zips_features.features)
.join("path")
.attr("stroke", "black")
.attr("stroke-linejoin", "round")
.attr("stroke-width", 0.2)
.attr("fill", function(d){
if(data.get(+d.properties.zip5) >= 0){
return quantile(data.get(+d.properties.zip5));
}
else{
return nancolor;
}
})
// .attr("fill", d => quantile(data.get(+d.properties.zip5)))
.attr("d", path)
.append("title")
.text(d => " Proportion of Providers: " + data.get(+d.properties.zip5));
return svg.node();
}
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