md`# Second Exercise on Observable: Classification and Colors`
d3 = require("d3@5")
topojson = require("topojson-client@3")
schooldistricts = FileAttachment("Iowa_School_Districts_2023-2024.json").json()
schooldistricts_features = topojson.feature(schooldistricts, schooldistricts.objects.Iowa_School_Districts_2023-2024)
csv_data = d3.csvParse(await FileAttachment("Iowa_School_Districts_2023-2024 (1).csv").text(),({SchoolDist, Pop2020, SqMiles}) => [SchoolDist, [+Pop2020/+SqMiles]])
csv_data_objects = Object.assign((d3.csvParse(await FileAttachment("Iowa_School_Districts_2023-2024 (1).csv").text(), d3.autoType)).map(({SchoolDist, Pop2020, SqMiles}) => ({SchoolDist: +SchoolDist, popdensity: +Pop2020/+SqMiles})))
Plot.plot({
marks: [
Plot.rectY(csv_data_objects, Plot.binX({y: "count"}, {x: "popdensity", thresholds: bins})),
Plot.ruleY([0])
]
})
popdensity = Array.from(csv_data.values(), d => d[1])
data = Object.assign(new Map(csv_data), {title: ["Iowa School Districts 2023-2024", "Population Density"]})
md`# Linear Scale (Unclassed)`
linear = d3.scaleLinear()
.domain(d3.extent(popdensity))
.range(["white", "red"])
chart(numericSort(popdensity), linear)
md`# Quantile Classification`
quantile = d3.scaleQuantile()
.domain(popdensity)
.range(["white", "#fb6a4a", "red"])
chart(numericSort(popdensity), quantile)
md`# Jenks Natural Breaks Classification`
naturalbreaks = simple.ckmeans(popdensity, 3).map(v => v.pop())
jenks = d3
.scaleThreshold()
.domain(naturalbreaks)
.range(["white", "#fb6a4a", "red"])
chart(numericSort(popdensity), jenks)
md`# Equal Interval Classification (Quantize)`
quantize = d3.scaleQuantize()
.domain([d3.min(popdensity),d3.max(popdensity)])
.range(["#fee0d2", "#fc9272", "#de2d26"])
chart(numericSort(popdensity), quantize)
md`# Threshold`
threshold = d3.scaleThreshold()
.domain([0.05, 0.1, 0.2])
.range(["white", "#fb6a4a", "red"])
chart(numericSort(popdensity), threshold)
showScaleGrouping(popdensity, {
scaleQuantile: quantile,
scaleThreshold: threshold,
scaleJenks: jenks,
scaleQuantize: quantize,
scaleQuantizeNice: quantize.copy().nice()
})
md`# Annex`
simple = require("simple-statistics@7.0.7/dist/simple-statistics.min.js")
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