BBox Collision Detection

d3.forceSimulation bounding box collision detection. This is useful for label adjustment or rectangular nodes. Each node receives a bounding box array of a top right and bottom left corner of that node relative to its x position. In the case of this dataset, that size is based on the length of the word in the source dataset.

A function for calculating this array based off the data isis passed into the forceRectCollide function, which is later passed as a "collide" constraint in your force settings.

var collide = d3.forceRectCollide(function (d,i) {
    var hw = halfWidth(d)
    if (i%3 === 0) {
      return [[-hw / 2, -hw],[hw / 2, hw]]
    }
    return [[-hw, -hw / 2],[hw,hw / 2]]
  })
  .strength(1)
  .iterations(2)

The code above creates a vertical or horizontal rectangle. Make sure you make your corresponding on-screen rectangle match the size of your constraint.

<html>
<head>
  <title>Bounding Box Collision</title>
  <meta charset="utf-8" />
<script src="https://d3js.org/d3.v4.min.js"></script>
<script src="d3-force.js"></script>
</head>
<style>
  svg {
    height: 1000px;
    width: 1000px;
    border: 1px solid gray;
  }
</style>
<body>

d3.csv("words.csv",function(error,data) {createWordcloud(data)});

function createWordcloud(data) {

var networkCenter = d3.forceCenter().x(500).y(500);

var textScale = d3.scaleLinear().domain([10,70]).range([2,30])

var forceX = d3.forceX(function (d) {return 500})
    .strength(function (d) {return textScale(d.frequency) * 0.001})

var forceY = d3.forceY(function (d) {return 500})
    .strength(function (d) {return textScale(d.frequency) * 0.001})

function halfWidth(d) {
  return d.text.length * textScale(d.frequency)
}

var collide = d3.forceRectCollide(function (d,i) {
    var hw = halfWidth(d)
    if (i%3 === 0) {
      return [[-hw / 2, -hw],[hw / 2, hw]]
    }
    return [[-hw, -hw / 2],[hw,hw / 2]]
  })
  .strength(1)
  .iterations(2)

var color = d3.scaleOrdinal(d3.schemeCategory10)

var force = d3.forceSimulation(data)
    .velocityDecay(0.6)
    .force("center", networkCenter)
    .force("x", forceX)
    .force("y", forceY)
    .force("collide", collide)
    .on("tick", updateNetwork);

var nodeEnter = d3.select("svg.main")
  .append("g")
  .selectAll("g.node")
  .data(data)
  .enter()
  .append("g")
  .attr("class", "node")

nodeEnter.append("rect")
    .attr("class", "base")
    .style("stroke-width", 1)
    .style("stroke", function (d, i) {return d3.color(color(i)).brighter(2)})
    .each(function (d,i) {
      var hw = halfWidth(d)
      if (i%3 === 0) {
        d3.select(this)
        .style("fill", color(i))
        .attr("x", -hw / 2)
        .attr("y", -hw)
        .attr("height", hw * 2)
        .attr("width", hw)
      }
      else {
        d3.select(this)
        .style("fill", d3.color(color(i)).darker(2))
        .attr("y", -hw / 2)
        .attr("x", -hw)
        .attr("width", hw * 2)
        .attr("height", hw)
      }
    })

function updateNetwork() {
    d3.select("svg.main").selectAll("g.node")
      .attr("transform", function (d) {return "translate(" + d.x + "," + d.y + ")"})
  }

}
</script>
  </footer>

</html>

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