mbostock · March 8, 2024 10:40 · Nov 14, 2016 · Nov 14, 2016 · Nov 14, 2016
diff --git a/package.json b/package.json
@@ -11,13 +11,11 @@
   "devDependencies": {
     "d3-array": "^1.0.1",
     "d3-geo-projection": "^1.2.1",
+    "d3-scale-chromatic": "^1.1.0",
     "ndjson-cli": "^0.3.0",
     "shapefile": "^0.5.8",
     "topojson": "^2.0.0",
     "topojson-client": "^2.1.0",
     "topojson-simplify": "^2.0.0"
-  },
-  "dependencies": {
-    "d3-scale-chromatic": "^1.1.0"
   }
 }
diff --git a/legend.svg b/legend.svg
diff --git a/topo.svg b/topo.svg
diff --git a/.block b/.block
@@ -0,0 +1,3 @@
+license: gpl-3.0
+height: 1100
+border: no
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1,3 @@
+.DS_Store
+node_modules
+cb_*
diff --git a/README.md b/README.md
@@ -0,0 +1 @@
+This variation of my [California population density map](/mbostock/39b34968ad5eab65de1d7da81f78bb27) uses [geo2svg](https://github.com/d3/d3-geo-projection/blob/master/README.md#geo2svg) to generate a static choropleth from the command line!
diff --git a/index.html b/index.html
@@ -0,0 +1,2 @@
+<!DOCTYPE html>
+<img src="topo.svg" width="960" height="1100">
diff --git a/legend.svg b/legend.svg
diff --git a/package.json b/package.json
@@ -0,0 +1,23 @@
+{
+  "private": true,
+  "license": "gpl-3.0",
+  "author": {
+    "name": "Mike Bostock",
+    "url": "https://bost.ocks.org/mike"
+  },
+  "scripts": {
+    "prepublish": "bash prepublish"
+  },
+  "devDependencies": {
+    "d3-array": "^1.0.1",
+    "d3-geo-projection": "^1.2.1",
+    "ndjson-cli": "^0.3.0",
+    "shapefile": "^0.5.8",
+    "topojson": "^2.0.0",
+    "topojson-client": "^2.1.0",
+    "topojson-simplify": "^2.0.0"
+  },
+  "dependencies": {
+    "d3-scale-chromatic": "^1.1.0"
+  }
+}
diff --git a/prepublish b/prepublish
@@ -0,0 +1,90 @@
+#!/bin/bash
+
+# EPSG:3310 California Albers
+PROJECTION='d3.geoAlbers().parallels([34, 40.5]).rotate([120, 0])'
+
+# The state FIPS code.
+STATE=06
+
+# The ACS 5-Year Estimate vintage.
+YEAR=2014
+
+# The display size.
+WIDTH=960
+HEIGHT=1100
+
+# Download the census block group boundaries.
+# Extract the shapefile (.shp) and dBASE (.dbf).
+if [ ! -f cb_${YEAR}_${STATE}_bg_500k.shp ]; then
+  curl -o cb_${YEAR}_${STATE}_bg_500k.zip \
+    "http://www2.census.gov/geo/tiger/GENZ${YEAR}/shp/cb_${YEAR}_${STATE}_bg_500k.zip"
+  unzip -o \
+    cb_${YEAR}_${STATE}_bg_500k.zip \
+    cb_${YEAR}_${STATE}_bg_500k.shp \
+    cb_${YEAR}_${STATE}_bg_500k.dbf
+fi
+
+# Download the list of counties.
+if [ ! -f cb_${YEAR}_${STATE}_counties.json ]; then
+  curl -o cb_${YEAR}_${STATE}_counties.json \
+    "http://api.census.gov/data/${YEAR}/acs5?get=NAME&for=county:*&in=state:${STATE}&key=${CENSUS_KEY}"
+fi
+
+# Download the census block group population estimates for each county.
+if [ ! -f cb_${YEAR}_${STATE}_bg_B01003.ndjson ]; then
+  for COUNTY in $(ndjson-cat cb_${YEAR}_${STATE}_counties.json \
+      | ndjson-split \
+      | tail -n +2 \
+      | ndjson-map 'd[2]' \
+      | cut -c 2-4); do
+    echo ${COUNTY}
+    if [ ! -f cb_${YEAR}_${STATE}_${COUNTY}_bg_B01003.json ]; then
+      curl -o cb_${YEAR}_${STATE}_${COUNTY}_bg_B01003.json \
+        "http://api.census.gov/data/${YEAR}/acs5?get=B01003_001E&for=block+group:*&in=state:${STATE}+county:${COUNTY}&key=${CENSUS_KEY}"
+    fi
+    ndjson-cat cb_${YEAR}_${STATE}_${COUNTY}_bg_B01003.json \
+      | ndjson-split \
+      | tail -n +2 \
+      >> cb_${YEAR}_${STATE}_bg_B01003.ndjson
+  done
+fi
+
+# 1. Convert to GeoJSON.
+# 2. Project.
+# 3. Join with the census data.
+# 4. Compute the population density.
+# 5. Simplify.
+# 6. Compute the county borders.
+geo2topo -n \
+  blockgroups=<(ndjson-join 'd.id' \
+    <(shp2json cb_${YEAR}_${STATE}_bg_500k.shp \
+      | geoproject "${PROJECTION}.fitExtent([[10, 10], [${WIDTH} - 10, ${HEIGHT} - 10]], d)" \
+      | ndjson-split 'd.features' \
+      | ndjson-map 'd.id = d.properties.GEOID.slice(2), d') \
+    <(cat cb_${YEAR}_${STATE}_bg_B01003.ndjson \
+    | ndjson-map '{id: d[2] + d[3] + d[4], B01003: +d[0]}') \
+    | ndjson-map -r d3=d3-array 'd[0].properties = {density: d3.bisect([1, 10, 50, 200, 500, 1000, 2000, 4000], (d[1].B01003 / d[0].properties.ALAND || 0) * 2589975.2356)}, d[0]') \
+  | topomerge -k 'd.id.slice(0, 3)' counties=blockgroups \
+  | topomerge --mesh -f 'a !== b' counties=counties \
+  | topomerge -k 'd.properties.density' blockgroups=blockgroups \
+  | toposimplify -p 1 -f \
+  > topo.json
+
+# Convert to SVG (while dropping the last line).
+cat \
+  <(topo2geo -n \
+    < topo.json blockgroups=- \
+    | ndjson-map -r d3=d3-scale-chromatic '(d.properties.title = d.id, d.properties.fill = d3.schemeOrRd[9][d.id], d)') \
+  <(topo2geo -n \
+    < topo.json counties=- \
+    | ndjson-map '(d.properties.stroke = "black", d.properties.strokeOpacity = 0.3, d)') \
+  | geo2svg --stroke=none -n -p 1 -w ${WIDTH} -h ${HEIGHT} \
+  | sed '$d' \
+  > topo.svg
+
+# Insert the legend.
+tail -n +4 \
+  < legend.svg \
+  >> topo.svg
+
+rm topo.json
diff --git a/preview.jpg b/preview.jpg
diff --git a/thumbnail.png b/thumbnail.png
diff --git a/topo.svg b/topo.svg
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1 @@
		This variation of my [California population density map](/mbostock/39b34968ad5eab65de1d7da81f78bb27) uses [geo2svg](https://github.com/d3/d3-geo-projection/blob/master/README.md#geo2svg) to generate a static choropleth from the command line!
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		<!DOCTYPE html>
		<img src="topo.svg" width="960" height="1100">