County-level data for Oregon:
Preview shapefiles:
Geographic projections:
Fetch Oregon county shapes
mkdir formatted rawmv ~/Downloads/tl_2010_41_county10.zip ./raw/unzip -o raw/tl_2010_41_county10.zip
Fetch population data by county
curl 'https://api.census.gov/data/2015/acs5?get=B01003_001E&for=county:*&in=state:41' -o raw/or-county-populations.json
Convert county data JSON array to an NDJSON stream
ndjson-cat: remove newlinesndjson-split: split into multiple linesndjson-map: reformat each line as an object
ndjson-cat raw/or-county-populations.json \ | ndjson-split 'd.slice(1)' \ | ndjson-map '{id: d[2], population: d[0]}' \ > formatted/or-county-populations.ndjson
Convert shapefile to GeoJSON and apply a geographic projection
shp2json raw/tl_2010_41_county10.shp \ | geoproject 'd3.geoConicConformal().parallels([44 + 20 / 60, 46]).rotate([120 + 30 / 60, 0]).fitSize([960, 960], d)' \ > formatted/or-projected.json
Preview in a browser
geo2svg -w 960 -h 960 < formatted/or-projected.json > formatted/or-projected.svg
Convert the GeoJSON feature collection to a newline-delimited stream of GeoJSON features,then set each feature’s id usingndjson-map:
ndjson-split 'd.features' \ < formatted/or-projected.json \ | ndjson-map 'd.id = d.properties.COUNTYFP10, d' \ > formatted/or-projected-id.ndjson
Join the population data to the geometry using ndjson-join,and remove the props we don't need
ndjson-join 'd.id' formatted/or-county-populations.ndjson formatted/or-projected-id.ndjson \ | ndjson-map 'd[1].properties = {population: d[0].population}, d[1]' \ > formatted/or-joined.ndjson
Now, perform some topology-preserving simplification, topoquantize, and delta-encode
geo2topo -n \ counties=formatted/or-joined.ndjson \ | topoquantize 1e5 \ > formatted/or-topo.json
We need a non-linear transform to distribute the colors equitably, so we'll use a threshold scale.Usetopo2geo to extract the simplified counties from the topology,pipe tondjson-map to assign the fill property for each county,pipe tondjson-split to break the collection into features,and lastly pipe togeo2svg
topo2geo counties=- \ < formatted/or-topo.json \ | ndjson-map -r d3 -r d3=d3-scale-chromatic 'z = d3.scaleThreshold().domain([1000, 10000, 25000, 50000, 100000, 300000, 600000]).range(d3.schemeOrRd[9]), d.features.forEach(f => f.properties.fill = z(f.properties.population)), d' \ | ndjson-split 'd.features' \ | geo2svg -n --stroke none -p 1 -w 960 -h 960 \ > formatted/or-counties-threshold.svg
