Cartogram to Bubble Chart

Taking advantage of the forceSimulation-based nature of the cartogram to switch to a bubble chart using the same data.

Demographics from http://library.duke.edu/data/collections/popest

<!DOCTYPE html>
  <html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>Force-Based Cartogram to Bubble Chart</title>
    <style>
      body {
        padding: 0;
        margin: 0;
      }

</style>
  </head>
  <body>

var colors = [
"#d0d9c4",
"#dfa3ad",
"#d0915b",
"#a9573f",
"#844e5e"
]

var selectedValue = "tot_pop"
var selectedIndex = 0
var sizeRange = [1.5,50]
var notcarto = true

d3.csv("county_demo.csv", cartogram)

function cartogram(data) {

var dataKeys = Object.keys(keys)

data.forEach(d => {
    dataKeys.forEach(k => {
      d[k] = parseInt(d[k])
    })
  })

var thisKeyValues = data.map(d => d[selectedValue])

var extent = d3.extent(thisKeyValues)

var scale = d3.scaleLinear().domain(extent).range(sizeRange)
  var colorScale = d3.scaleCluster().domain(thisKeyValues).range(colors)

var force = d3.forceSimulation()
  .force("collision", d3.forceCollide(d => scale(d[selectedValue])).iterations(2))
  .force("x", d3.forceX(d => d.cx))
  .force("y", d3.forceY(d => d.cy))
  .nodes(data)
  .alphaMin(0.25)
  .on("tick", updateCartogram)
  .on("end", resetCartogram)

d3.select("svg")
    .selectAll("circle.node")
    .data(data)
    .enter()
    .append("circle")
    .attr("class", "node")
    .style("stroke-width", 2)

d3.select("svg").append("text")
    .style("text-anchor", "middle")
    .attr("class", "title")
    .text("Total Population")
    .style("font-size", "36px")
    .attr("x", 600)
    .attr("y", 50)

redrawNodes()

function updateCartogram() {
    d3.selectAll("circle.node")
      .attr("cx", d => d.x)
      .attr("cy", d => d.y)
  }

function resetCartogram() {
    if (notcarto) {
      selectedIndex = selectedIndex === dataKeys.length ? 0 : selectedIndex + 1
      selectedValue = dataKeys[selectedIndex]
      d3.select("text.title")
        .text(keys[selectedValue])

thisKeyValues = data.map(d => d[selectedValue])
      extent = d3.extent(thisKeyValues)

scale = d3.scaleLinear().domain(extent).range(sizeRange)
      colorScale = d3.scaleCluster().domain(thisKeyValues).range(colors)

redrawNodes()
      force.force("collision", d3.forceCollide(d => scale(d[selectedValue])).iterations(2))
      .force("x", d3.forceX(d => d.cx))
      .force("y", d3.forceY(d => d.cy))
      .alpha(1)
      .restart()

}
    else {
      var positionScale = d3.scaleCluster().domain(thisKeyValues).range([200,400,600,800,1000])
      force
      .force("x", d3.forceX(d => positionScale(d[selectedValue])))
      .force("y", d3.forceY(400))
      .alpha(1)
      .restart()

}
      notcarto = !notcarto
  }

function redrawNodes() {
    d3.selectAll("circle.node")
      .transition()
      .duration(500)
      .style("fill", d => colorScale(d[selectedValue]))
      .style("stroke", d => d3.hsl(colorScale(d[selectedValue])).darker())
      .attr("r", d => scale(d[selectedValue]))

}

</script>

https://d3js.org/d3.v4.min.js

https://unpkg.com/d3-scale-cluster@1.1.7/dist/d3-scale-cluster.min.js