D3 Examples - Custom Beeswarm & ForceLayout

Custom Beeswarm & ForceLayout
This block is a continuation of a previous one.
This sequel 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
This block produces a beeswarm in 2 stages:
define a first arrangement using a custom algorythm (cf. previous block)
then, use the ForceLayout in order to group extreme accumulations, or constraint the arrangement to a certain size
The ForceLayout is used only few times (5 iterations by default) in order to handle computation time. For comparison, with 600 points:
~1200 ms <== Force only with ~300 iterations
~ 100 ms <== custom only | extreme acc., no overlap, fast
~ 150 ms <== custom (100ms) + force with 5 iterations (50ms) |some overlap, no extreme acc., fast
~ 150ms <== Force only with ~20 iterations | cons: not so beautiful, some overlap, no extreme acc., fast
Acknowledgments to:
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<!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 src="https://cdnjs.cloudflare.com/ajax/libs/dat-gui/0.5.1/dat.gui.min.js"></script>
  <script>
    var width = 960,
        height = 500;
    var csvData = [];
        var config = {
      radius: 4,
      use_it: true,
      iterations: 5,
      gravity: 0.4,
      manyPoints: true
    };
​
    insertControls();
    
    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("id", "x-axis")
      .attr("x1", 0)
      .attr("y1", height/2)
      .attr("x2", width)
      .attr("y2", height/2)
      .style("stroke", "lightgrey");
    
    var nodeContainer = svg.append("g").attr("id", "node-container");
        
    var informationPanel, computationTimeInfo, dataLengthInfo, posibleCollidersInfo, placementInfo, visitedCollidersInfo;
    prepareInformationPanel();
        
    var tooltip, stem, rank, value;
    prepareTooltip();
    
    var minDistanceBetweenCircles,
      minSquareDistanceBetweenCircles,
      AAD,
      totalPossibleCollders, maxPossibleColliders,
      totalTestedPlacements,
      visitedColliderCount, totalVisitedColliders, maxVisitedColliders;
    
        function initPlacement() {
      minDistanceBetweenCircles = 2*config.radius;
      minSquareDistanceBetweenCircles = Math.pow(minDistanceBetweenCircles, 2);
      AAD = []; //already arranged data; window for collision detection
      //-->for metrics purpose
      totalPossibleColliders = maxPossibleColliders = 0;
      totalTestedPlacements = 0;
      visitedColliderCount = totalVisitedColliders = maxVisitedColliders =0;
      //<--for metrics purpose
    };
    
    function findPossibleColliders (datum) {
      //remove circles from AAD that are far away from datum
      var indexesToRemove = 0;
      AAD.every(function (aad) {
        if (Math.abs(datum.x-aad.x)>minDistanceBetweenCircles) {
          indexesToRemove++;
          return true;
        }
        return false;
      });
      AAD.splice(0,indexesToRemove);
      
      //-->for metrics purpose
      totalPossibleColliders += AAD.length;
      if (AAD.length > maxPossibleColliders) {
        maxPossibleColliders = AAD.length;
      }
      //<--for metrics purpose
    }
​
    function isBetterPlacement(datum, bestYPosition) {
      return Math.abs(datum.y) < Math.abs(bestYPosition);
    }
​
    function yPosRelativeToAad(aad, d) {
      // handle Float approximation with +1E-6
      return Math.sqrt(minSquareDistanceBetweenCircles-Math.pow(d.x-aad.x,2))+1E-6;
    }
​
    function placeBelow(d, aad, relativeYPos) {
      d.y = aad.y - relativeYPos;
    }
​
    function placeAbove(d, aad, relativeYPos) {
      d.y = aad.y + relativeYPos;
    }
​
    function areCirclesColliding(d0, d1) {
      visitedColliderCount++ //for metrics prupose
      
      //first simple check (vertical positions)
      if (Math.abs(d1.y - d0.y) > minDistanceBetweenCircles) return false;
      
      //more advanced check
      var squareDistanceBetweenCircles = Math.pow(d1.y-d0.y, 2) + Math.pow(d1.x-d0.x, 2);
      return squareDistanceBetweenCircles < minSquareDistanceBetweenCircles;
    }
​
    function collidesWithOther (data) {
      return AAD.some(function(aad) {
        return areCirclesColliding(aad, data);
      });
    }
​
    function placeCircles (data) {
      initPlacement();
      data.forEach(function (d) {
        var bestYPosition = -Infinity,
            relativeYPos;
        findPossibleColliders(d);
        if (AAD.length===0) {
          bestYPosition = 0;
        } else {
          AAD.forEach(function(aad) {
            relativeYPos = yPosRelativeToAad(aad, d);
            placeBelow(d, aad, relativeYPos);
            if (isBetterPlacement(d, bestYPosition) && !collidesWithOther(d)) {
              bestYPosition = d.y;
            }
            //-->for metrics purpose
              totalVisitedColliders += visitedColliderCount;
              if (visitedColliderCount > maxVisitedColliders) {
                maxVisitedColliders = visitedColliderCount;
              }
              visitedColliderCount = 0;
            //<--for metrics purpose
            placeAbove(d, aad, relativeYPos);
            if (isBetterPlacement(d, bestYPosition) && !collidesWithOther(d)) {
              bestYPosition = d.y;
            }
            //-->for metrics purpose
              totalVisitedColliders += visitedColliderCount;
              if (visitedColliderCount > maxVisitedColliders) {
                maxVisitedColliders = visitedColliderCount;
              }
              visitedColliderCount = 0;
            //<--for metrics purpose
                totalTestedPlacements += 2; //for metrics purpose
          })
        };
        d.y = bestYPosition;
        AAD.push(d);
      });
    }
​
    function showCircles (data) {
      nodeContainer.selectAll("circle").remove();
      var node = nodeContainer.selectAll("circle")
          .data(data)
        .enter().append("circle")
          .attr("r", config.radius-0.75)
          .attr("cx", function(d) { return d.x; })
          .attr("cy", function(d) { return 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 applyForceLayout (data) {
      //prepare data for ForceLayout
      data.forEach(function(d) {
        d.y += height/2;
      })
      
      var force = d3.layout.force()     
        .gravity(config.gravity)    
        .charge(-(config.radius*config.radius-config.radius))
        .size([width, height])      
        .friction(0.7)
​
      function tick() {
        data.forEach(function(d){ d.x = d.originalX; }) //constrains x-position
      }
​
      force.nodes(data)
        .on("tick", tick)
        .stop();
​
      force.start();
      for (var i = 0; i < config.iterations; i++) { force.tick(); }
      force.stop();
    }
    
    function drawBeeswarm() {
      var data = config.manyPoints? double(double(copyCsvData())) : copyCsvData();
       
      var startTime = Date.now();
      if (config.use_it) {
          placeCircles(data);
        //showMetrics(data, (Date.now()-startTime));
      }
      
      applyForceLayout(data);
      
      showCircles(data);
    }
​
    function dottype(d) {
      d.stem = d.stem;
      d.rank = +d.rank;
      d.trend = +d.trend;
      d.originalX = width/2+d.trend*6000;
      d.x = d.originalX;
      d.y = 0;
      csvData.push(d);
      return d;
    }
    
    d3.csv("data.csv", dottype, function(error, foo) {
      if (error) throw error;
      drawBeeswarm()
    });
    
    function copyCsvData() {
      return csvData.map(function(d) {
          return {
            stem: d.stem,
            rank: d.rank,
            trend: d.trend,
            originalX: d.originalX,
            x: d.originalX,
            y: d.y
          }
         });
    }
​
    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,
          originalX: d.originalX+1E-3,
          x: d.originalX+1E-3,
          y: d.y
        })
        doubledData.push(d);
      })
      return doubledData;
    }
    
    function insertControls () {
      var ctrls = new dat.GUI({width: 200});
      var customArrangementCtrl = ctrls.addFolder("Step1 - Custom Arrangement");
      customArrangementCtrl.open();
      var applyCustomArrangementCtrl = customArrangementCtrl.add(config, "use_it");
      applyCustomArrangementCtrl.onChange(function(value) {
        drawBeeswarm();
      });
      var forceCtrl = ctrls.addFolder("Step2 - Force Layout");
      forceCtrl.open();
      var iterationCountCtrl = forceCtrl.add(config, "iterations", 0, 50);
      iterationCountCtrl.step(1).onChange(function(value) {
        drawBeeswarm();
      });
      var gravityCtrl = forceCtrl.add(config, "gravity", 0, 1);
      gravityCtrl.onChange(function(value) {
        drawBeeswarm();
      });
      var manyPointsCtrl = ctrls.add(config, "manyPoints");
      manyPointsCtrl.onChange(function(value) {
        drawBeeswarm();
      });
    }
    
    function prepareTooltip() {
      tooltip = svg.append("g")
        .attr("id", "tooltip")
        .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]+")")
      stem = values.append("text")
        .attr("text-anchor", "start");
      rank = values.append("text")
        .attr("text-anchor", "start")
        .attr("transform", "translate("+[0,15]+")");
      value = values.append("text")
        .attr("text-anchor", "start")
        .attr("transform", "translate("+[0,30]+")");
    }
    
    function prepareInformationPanel() {
      var i=4;
      informationPanel = svg.append("g")
        .attr("id", "infomation-panel")
        .attr("transform", "translate("+[width-20, height-20]+")");
      computationTimeInfo = informationPanel.append("text")
        .attr("text-anchor", "end")
        .attr("transform", "translate("+[0,-15*i--]+")");
      dataLengthInfo = informationPanel.append("text")
        .attr("text-anchor", "end")
        .attr("transform", "translate("+[0,-15*i--]+")");
      possibleCollidersInfo = informationPanel.append("text")
        .attr("text-anchor", "end")
        .attr("transform", "translate("+[0,-15*i--]+")");
      placementInfo = informationPanel.append("text")
        .attr("text-anchor", "end")
        .attr("transform", "translate("+[0,-15*i--]+")");
      visitedCollidersInfo = informationPanel.append("text")
        .attr("text-anchor", "end");
    }
    
    function showMetrics (data, elapsed) {
      //-->for metrics purpose
      computationTimeInfo.text("Arrangement took: "+elapsed+" ms");
      dataLengthInfo.text("# data: "+data.length);
      possibleCollidersInfo.text("# possible colliders: ~"+Math.round(totalPossibleColliders/data.length)+" per data ("+maxPossibleColliders+" max, "+totalPossibleColliders+" total)");
      placementInfo.text("# tested placements: "+totalTestedPlacements);
      visitedCollidersInfo.text("# collision checks: "+
      totalVisitedColliders);
      //>--for metrics purpose
    }
  </script>
</body>
    