Custom Beeswarm II (perf. enhancement)

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 (handle overlapping)

Compared to the previous block, this algorithm is ~2 times faster, because:

computing possible colliders is faster
when placing a new circle, collision detection (which iterates over already drawn circles) is executed if and only if the new tested placement is better than the one already found (gain is ~40%)
collision detection is faster (now stoping at first collision)

The algorithm is:

loop1 - for each new circle to place Ci:
find 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 is a better placement than the already tested (best = closest to x-axis, consider absolute value)
  - if Ci does not overlap others circles in AAC
    - retain y-position as the best till now
- place Ci below Ca
- if Ci is a better placement than the already tested
  - if Ci does not overlap others circles in AAC
    - retain y-position as the best till now
place Ci at best y-position, add Ci to AAC

Acknowledgments to:

<!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 trendData = [];
		var config = {
      radius: 4,
      manyPoints: false
    };

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 dottype(d) {
      d.id = d.stem;
      d.stem = d.stem;
      d.rank = +d.rank;
      d.trend = +d.trend;
      d.x = width/2+d.trend*6000;
      d.y = 0;
      trendData.push(d);
      return d;
    }
    
    d3.csv("data.csv", dottype, function(error, data) {
      if (error) throw error;
      drawBeeswarm()
    });

https://d3js.org/d3.v3.min.js

https://cdnjs.cloudflare.com/ajax/libs/dat-gui/0.5.1/dat.gui.min.js