Adjacency Matrix from Node/Edge List

An adjacency matrix is a useful way of visualizing networks using an n-by-n grid that shows connection between nodes as a filled grid square. This adjacency matrix is directed, with the source on the y-axis and target on the x-axis. It loads the data from a node list and edge list and represents edge weight using opacity. It also highlights rows and columns on mouseover.

<html xmlns="https://www.w3.org/1999/xhtml">
<head>
  <title>D3 in Action Adjacency Matrix</title>
  <meta charset="utf-8" />
</head>
<script src="https://d3js.org/d3.v3.min.js" charset="utf-8"></script>
<script src="https://d3js.org/queue.v1.min.js" type="text/javascript"></script>
<style>
.tick line {
  shape-rendering: crispEdges;
  stroke: #000;
}

line.minor  {
  stroke: #777;
  stroke-dasharray: 2,2;
}

path.domain {
  fill: none;
  stroke: black;
}

</style>
<body onload="adjacency()">

<div id="vizcontainer">
<svg style="width:500px;height:500px;border:1px lightgray solid;" />
</div>
  <footer>
<script>
  
  function adjacency() {

queue()
    .defer(d3.csv, "nodelist.csv")
    .defer(d3.csv, "edgelist.csv")
    .await(function(error, file1, file2) { createAdjacencyMatrix(file1, file2); });
    
    function createAdjacencyMatrix(nodes,edges) {
      var edgeHash = {};
      for (x in edges) {
        var id = edges[x].source + "-" + edges[x].target;
        edgeHash[id] = edges[x];
      }
      matrix = [];
      //create all possible edges
      for (a in nodes) {
        for (b in nodes) {
          var grid = {id: nodes[a].id + "-" + nodes[b].id, x: b, y: a, weight: 0};
          if (edgeHash[grid.id]) {
            grid.weight = edgeHash[grid.id].weight;
          }
          matrix.push(grid);
        }
      }
      
      d3.select("svg")
      .append("g")
      .attr("transform", "translate(50,50)")
      .attr("id", "adjacencyG")
      .selectAll("rect")
      .data(matrix)
      .enter()
      .append("rect")
      .attr("width", 25)
      .attr("height", 25)
      .attr("x", function (d) {return d.x * 25})
      .attr("y", function (d) {return d.y * 25})
      .style("stroke", "black")
      .style("stroke-width", "1px")
      .style("fill", "red")
      .style("fill-opacity", function (d) {return d.weight * .2})
      .on("mouseover", gridOver)
      
      var scaleSize = nodes.length * 25;
      var nameScale = d3.scale.ordinal().domain(nodes.map(function (el) {return el.id})).rangePoints([0,scaleSize],1);
      
      xAxis = d3.svg.axis().scale(nameScale).orient("top").tickSize(4);    
      yAxis = d3.svg.axis().scale(nameScale).orient("left").tickSize(4);    
      d3.select("#adjacencyG").append("g").call(xAxis).selectAll("text").style("text-anchor", "end").attr("transform", "translate(-10,-10) rotate(90)");
      d3.select("#adjacencyG").append("g").call(yAxis);
      
      function gridOver(d,i) {
        d3.selectAll("rect").style("stroke-width", function (p) {return p.x == d.x || p.y == d.y ? "3px" : "1px"})
      }

}
    
  }
  </script>
  </footer>
</body>
</html>

Modified http://d3js.org/d3.v3.min.js to a secure url

Modified http://d3js.org/queue.v1.min.js to a secure url

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

https://d3js.org/queue.v1.min.js