D3 Examples - Custom Beeswarm

Custom Beeswarm

This block experiments a way to vizualise the distribution of things (whatever it is) in a horizontal way (ie. along the x-axis), where constraints/objectives are:

to maintain the exact position of each datum (represented by a circle) along the x-axis

to be able to hover each circle to show related datum (handle overlapping)

In previous blocks (1, 2), I tried the Force Layout.

Now I try to implement my own arrangement algorithm (with the secret objective that it will be faster than using the Force O_° ... and, hopefully, it is).

The resulting arrangement can be used as-is (shown in this example), or can be a good starting point before applying the Force. In this later case, final arrangement with the Force will be obtained faster than with the random default arrangment.

The algorithm is:

(hyp) circles to draw are ordered (from right to left in this example)

(init) already arranged circles AAC = [], used for (windowed) collision detection

loop1 - for each new circle to place Ci:

retain in AAC only already drawn circles susceptible to overlap (close enought to Ci, distance from Ci <= 2*r)

if AAC is empty, place Ci on the x-axis (Ci.y = 0), push Ci in AAC, continue loop1

loop2 - for each Ca in AAC:

place Ci above Ca
if Ci does not overlap others circles in AAC, retain y-position if it is the best till now(best = closest to x-axis, consider absolute value)
place Ci below Ca
if Ci does not overlap others circles in AAC, retain y-position if it is the best till now

place Ci at best y-position, add Ci to AAC

Acknowledgments to:

xxxxxxxxxx
 
<!DOCTYPE html>
<meta charset="utf-8">
<style>
  
  #under-construction {
    display: none;
    position: absolute;
    top: 200px;
    left: 300px;
    font-size: 40px;
  }
​
  circle {
    stroke-width: 1.5px;
  }
​
  line {
    stroke: #999;
  }
​
</style>
<body>
  <div id="under-construction">
    UNDER CONSTRUCTION
  </div>
<script src="https://d3js.org/d3.v3.min.js"></script>
<script>
    var width = 960,
        height = 500,
        radius = 4;
​
    var fill = d3.scale.linear().domain([1,150]).range(['lightgreen', 'pink']);
    
  var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);
    
  svg.append("line")
    .attr("x1", 0)
    .attr("y1", height/2)
    .attr("x2", width)
    .attr("y2", height/2)
    .style("stroke", "lightgrey");
  
    var tooltip = svg.append("g")
    .attr("transform", "translate("+[width/2, 50]+")")
    .style("opacity", 0);
  var titles = tooltip.append("g").attr("transform", "translate("+[-5,0]+")")
  titles.append("text").attr("text-anchor", "end").text("stem(fr):");
  titles.append("text")
    .attr("text-anchor", "end")
    .attr("transform", "translate("+[0,15]+")")
    .text("rank:");
  titles.append("text")
    .attr("text-anchor", "end")
    .attr("transform", "translate("+[0,30]+")")
    .text("x-value:");
  var values = tooltip.append("g").attr("transform", "translate("+[5,0]+")")
  var stem = values.append("text");
  stem.attr("text-anchor", "start");
  var rank = values.append("text");
  rank.attr("text-anchor", "start")
    .attr("transform", "translate("+[0,15]+")");
  var value = values.append("text");
  value.attr("text-anchor", "start")
    .attr("transform", "translate("+[0,30]+")");
  
  function dottype(d) {
    d.stem = d.stem;
    d.rank = +d.rank;
    d.trend = +d.trend;
    d.x = width/2+d.trend*6000;
    d.y = 0;
    return d;
  }
  
  minDistanceBetweenCircles = 2*radius;
  minSquareDistanceBetweenCircles = Math.pow(minDistanceBetweenCircles, 2);
  
  function areCirclesColliding(d0, d1) {
    if (d1.y===d0.y && d1.x===d0.x) return true;
    var squareDistanceBetweenCircles = Math.pow(d1.y-d0.y, 2) + Math.pow(d1.x-d0.x, 2);
    return squareDistanceBetweenCircles < minSquareDistanceBetweenCircles;
  }
  
  function collidesWithOthers (data) {
    var collidesWithOthers = false;
    AAD.forEach(function(aad) {
      if (areCirclesColliding(aad, data)) {
        collidesWithOthers = collidesWithOthers || true;
      }
    })
    return collidesWithOthers;
  }
  
  var AAD = []; //already arranged data; window for collision detection
  
  function cleanAAD (datum) {
    var indexesToRemove = 0;
    AAD.forEach(function (aad) {
      if (Math.abs(datum.x-aad.x)>minDistanceBetweenCircles) {
        indexesToRemove++;
      } else {
        return
      }
    })
    AAD.splice(0,indexesToRemove);
  }
  
  function yPosRelativeToAad(aad, d) {
    // return 2*radius; //issue: leave extra space when circles are not strictly vertically aligned
    
    return Math.sqrt(minSquareDistanceBetweenCircles+1E-6-Math.pow(d.x-aad.x,2));
  }
  
  function placeAbove(aad, d) {
    d.y = aad.y + yPosRelativeToAad(aad, d);
  }
  
  function placeBelow(aad, d) {
    d.y = aad.y - yPosRelativeToAad(aad, d);
  }
  
  function placeCircles (data) {
    data.forEach(function (d) {
      cleanAAD(d);
      if (AAD.length===0) {
        d.y = 0;
        AAD.push(d);
      } else {
            var bestYPosition = -Infinity,
            relativeY;
        AAD.forEach(function(aad) {
          placeBelow(aad, d);
          if (!collidesWithOthers(d)) {
            if (Math.abs(d.y) < Math.abs(bestYPosition)) {
                bestYPosition = d.y;
            } 
          }
          placeAbove(aad, d)
          if (!collidesWithOthers(d)) {
            if (Math.abs(d.y) < Math.abs(bestYPosition)) {
                bestYPosition = d.y;
            } 
          }
        })
        d.y = bestYPosition;
        AAD.push(d);
      }
    })
  }
  
  d3.csv("data.csv", dottype, function(error, trendData) {
    if (error) throw error;
​
    //trendData = double(double(trendData)); // test for scaling purpose
​
    var startTime = Date.now();
    placeCircles(trendData);
    console.log("arrangment took (ms): "+(Date.now()-startTime));
​
    var node = svg.selectAll("circle")
        .data(trendData)
      .enter().append("circle")
        .attr("r", radius-0.75)
        .attr("cx", function(d) { return d.x; })
        .attr("cy", function(d) { return height/2 + d.y; })
        .style("fill", function(d) { return fill(d.rank); })
        .style("stroke", function(d) { return d3.rgb(fill(d.rank)).darker(); })
        .on("mouseenter", function(d) {
          stem.text(d.stem);
          rank.text(d.rank);
          value.text(d.trend);
          tooltip.transition().duration(0).style("opacity", 1); // remove fade out transition on mouseleave
        })
            .on("mouseleave", function(d) {
          tooltip.transition().duration(1000).style("opacity", 0);
        });
  });
  
  function double(data) {
    // Doubles data while maintaining order 
    var doubledData = [];
    data.forEach(function(d) {
      doubledData.push({
        stem: d.stem,
        rank: d.rank,
        trend: d.trend,
        x: d.x+1E-3,
        y: d.y
      })
      doubledData.push(d);
    })
    return doubledData;
  }
​
</script>
​
    