Consensus Dynamics Diffusion

Instructions

Click the Reset button to generate new points.

Click the Next button to move to the next iteration.

Note: The x axis and y axis are not currently on the same scale.

forked from lwthatcher's block: Random Points II

<!DOCTYPE html>
<meta charset="utf-8">
<style> /* set the CSS */
  .point {
    fill: black;
  }

.t_old {
    fill: darkgrey
  }
  
.toolTip {
  pointer-events: none;
	position: absolute;
  display: none;
  width: 120px;
  height: auto;
  background: none repeat scroll 0 0 #ffffff;
  padding: 9px 14px 6px 14px;
  border-radius: 2px;
  text-align: center;
  line-height: 1.3;
  color: #5B6770;
  box-shadow: 0px 3px 9px rgba(0, 0, 0, .15);
}
.toolTip:after {
  content: "";
  width: 0;
  height: 0;
  border-left: 12px solid transparent;
  border-right: 12px solid transparent;
  border-top: 12px solid white;
  position: absolute;
  bottom: -10px;
  left: 50%;
  margin-left: -12px;
}  
.toolTip span {
	font-weight: 500;
  color: #081F2C;
}
</style>
<body>
    	
<script src="https://d3js.org/d3.v4.min.js"></script>
  <script src="https://www.numericjs.com/lib/numeric-1.2.6.js"></script>
<script>

// === Setup SVG ===
// set the dimensions and margins of the graph
var margin = {top: 20, right: 20, bottom: 30, left: 50},
    width = 900 - margin.left - margin.right,
    height = 450 - margin.top - margin.bottom;

// set the ranges
var x = d3.scaleLinear().range([0, width]);
var y = d3.scaleLinear().range([height, 0]);

// append the svg obgect to the body of the page
// appends a 'group' element to 'svg'
// moves the 'group' element to the top left margin
var svg = d3.select("body").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform",
          "translate(" + margin.left + "," + margin.top + ")");

// === Tooltip display functions ===
var tooltip = d3.select("body").append("div").attr("class", "toolTip");
var mouseover = (d) => {
  tooltip.style("opacity", 1.0)
        .style("left", x(d.x) - 15 + "px")
        .style("top", y(d.y) - 25 + "px")
        .style("display", "inline-block")
        .html("(" + d.x.toFixed(3) + ", " + d.y.toFixed(3) + ")" )
}
var mouseout = (d) => {
  tooltip.style("opacity", 0.0);
}

// === Consensus Dynamics Variables ===
// Graph Laplacian
var L = [[ 1,-1, 0],
         [-1, 2,-1],
         [ 0,-1, 1]];
  
// change rate
var dt = 0.09;

// === Diffusion Functions ===
// random point generator
var generate_random = function(num_agents) {
  var dataset = []
  for (var i = 0; i < num_agents; i++) {
    var x = d3.randomUniform(-50,50)();
    var y = d3.randomUniform(-50,50)();
    dataset.push({"x": x, "y": y});
  }
  return dataset
}
// gets next position
var update_position = function(Xt) {
  // convert to vector format
  var xt = Xt.map((n) => n["x"]);
  var yt = Xt.map((n) => n["y"]);
  
  // get derivaive
  var x_dot = numeric.dot(L, xt);
  var y_dot = numeric.dot(L, yt);
  
  // IMPORTANT: scale results by dt!
  x_dot = numeric.mul(x_dot, dt);
  y_dot = numeric.mul(y_dot, dt);
  
  // new point position
  var x_new = numeric.sub(xt, x_dot);
  var y_new = numeric.sub(yt, y_dot);
  
  // format result
  var result = []
  for(var i = 0; i < Xt.length; i++) {
    result[i] = {"x": x_new[i], "y":y_new[i]}
  }
  return result;
}

// === Drawing Stuff ===
var initialize = function() {
  // scale the range of the data
  x.domain([-50, 50]);
  y.domain([-50, 50]);
  
  // add the X Axis
  svg.append("g")
    .attr("transform", "translate(0," + height + ")")
    .call(d3.axisBottom(x));

// add the Y Axis
  svg.append("g")
    .call(d3.axisLeft(y));
}

// draws next iteration of convergence
var next = function() {
	old_points = svg.selectAll(".t_current");
  
  // fade old points
	old_points
  	.attr("class", "point t_old")
  	.attr("r", 4);
  
  // draw new points
  new_points = update_position(old_points.data());
  draw_points(new_points);
}

// === Run This on page-load ===
initialize();
reset();

</script>
  <button onclick="reset()">Reset</button>
  <button onclick="next()">Next</button>
</body>

Modified http://www.numericjs.com/lib/numeric-1.2.6.js to a secure url

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

https://www.numericjs.com/lib/numeric-1.2.6.js