How to calculate in-degree, out-degree and weigted degree for force directed graph (d3.js)?

Question

I am following this graph. How to calculated In-degree, out-degree and weighted graph using force directed graph.

Code:

var width = 960,
  height = 500;

var color = d3.scale.category20();

var force = d3.layout.force()
  .charge(-120)
  .linkDistance(30)
  .size([width, height]);

var svg = d3.select("body").append("svg")
  .attr("width", width)
  .attr("height", height);

d3.json("miserables.json", function(error, graph) {
  if (error) throw error;

  force
    .nodes(graph.nodes)
    .links(graph.links)
    .start();

  var link = svg.selectAll(".link")
    .data(graph.links)
    .enter().append("line")
    .attr("class", "link")
    .style("stroke-width", function(d) {
      return Math.sqrt(d.value);
    });

  var node = svg.selectAll(".node")
    .data(graph.nodes)
    .enter().append("circle")
    .attr("class", "node")
    .attr("r", 5)
    .style("fill", function(d) {
      return color(d.group);
    })
    .call(force.drag);

  node.append("title")
    .text(function(d) {
      return d.name;
    });

  force.on("tick", function() {
    link.attr("x1", function(d) {
        return d.source.x;
      })
      .attr("y1", function(d) {
        return d.source.y;
      })
      .attr("x2", function(d) {
        return d.target.x;
      })
      .attr("y2", function(d) {
        return d.target.y;
      });

    node.attr("cx", function(d) {
        return d.x;
      })
      .attr("cy", function(d) {
        return d.y;
      });
  });
});

.node {


  stroke: #fff;


  stroke-width: 1.5px;


}


.link {


  stroke: #999;


  stroke-opacity: .6;


}

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>

miserables.json

{
  "nodes":[
    {"name":"Myriel","group":1},
    {"name":"Napoleon","group":1},
    {"name":"Mlle.Baptistine","group":1},
    {"name":"Mme.Magloire","group":1},
    {"name":"CountessdeLo","group":1},
    {"name":"Geborand","group":1},
    {"name":"Champtercier","group":1},
    {"name":"Cravatte","group":1},
    {"name":"Count","group":1},
    {"name":"OldMan","group":1},
    {"name":"Labarre","group":2},
    {"name":"Valjean","group":2},
    {"name":"Marguerite","group":3},
    {"name":"Mme.deR","group":2},
    {"name":"Isabeau","group":2},
    {"name":"Gervais","group":2},
    {"name":"Tholomyes","group":3},
    {"name":"Listolier","group":3},
    {"name":"Fameuil","group":3},
    {"name":"Blacheville","group":3},
    {"name":"Favourite","group":3},
    {"name":"Dahlia","group":3},
    {"name":"Zephine","group":3},
    {"name":"Fantine","group":3},
    {"name":"Mme.Thenardier","group":4},
    {"name":"Thenardier","group":4},
    {"name":"Cosette","group":5},
    {"name":"Javert","group":4},
    {"name":"Fauchelevent","group":0},
    {"name":"Bamatabois","group":2},
    {"name":"Perpetue","group":3},
    {"name":"Simplice","group":2},
    {"name":"Scaufflaire","group":2},
    {"name":"Woman1","group":2},
    {"name":"Judge","group":2},
    {"name":"Champmathieu","group":2},
    {"name":"Brevet","group":2},
    {"name":"Chenildieu","group":2},
    {"name":"Cochepaille","group":2},
    {"name":"Pontmercy","group":4},
    {"name":"Boulatruelle","group":6},
    {"name":"Eponine","group":4},
    {"name":"Anzelma","group":4},
    {"name":"Woman2","group":5},
    {"name":"MotherInnocent","group":0},
    {"name":"Gribier","group":0},
    {"name":"Jondrette","group":7},
    {"name":"Mme.Burgon","group":7},
    {"name":"Gavroche","group":8},
    {"name":"Gillenormand","group":5},
    {"name":"Magnon","group":5},
    {"name":"Mlle.Gillenormand","group":5},
    {"name":"Mme.Pontmercy","group":5},
    {"name":"Mlle.Vaubois","group":5},
    {"name":"Lt.Gillenormand","group":5},
    {"name":"Marius","group":8},
    {"name":"BaronessT","group":5},
    {"name":"Mabeuf","group":8},
    {"name":"Enjolras","group":8},
    {"name":"Combeferre","group":8},
    {"name":"Prouvaire","group":8},
    {"name":"Feuilly","group":8},
    {"name":"Courfeyrac","group":8},
    {"name":"Bahorel","group":8},
    {"name":"Bossuet","group":8},
    {"name":"Joly","group":8},
    {"name":"Grantaire","group":8},
    {"name":"MotherPlutarch","group":9},
    {"name":"Gueulemer","group":4},
    {"name":"Babet","group":4},
    {"name":"Claquesous","group":4},
    {"name":"Montparnasse","group":4},
    {"name":"Toussaint","group":5},
    {"name":"Child1","group":10},
    {"name":"Child2","group":10},
    {"name":"Brujon","group":4},
    {"name":"Mme.Hucheloup","group":8}
  ],
  "links":[
    {"source":1,"target":0,"value":1},
    {"source":2,"target":0,"value":8},
    {"source":3,"target":0,"value":10},
    {"source":3,"target":2,"value":6},
    {"source":4,"target":0,"value":1},
    {"source":5,"target":0,"value":1},
    {"source":6,"target":0,"value":1},
    {"source":7,"target":0,"value":1},
    {"source":8,"target":0,"value":2},
    {"source":9,"target":0,"value":1},
    {"source":11,"target":10,"value":1},
    {"source":11,"target":3,"value":3},
    {"source":11,"target":2,"value":3},
    {"source":11,"target":0,"value":5},
    {"source":12,"target":11,"value":1},
    {"source":13,"target":11,"value":1},
    {"source":14,"target":11,"value":1},
    {"source":15,"target":11,"value":1},
    {"source":17,"target":16,"value":4},
    {"source":18,"target":16,"value":4},
    {"source":18,"target":17,"value":4},
    {"source":19,"target":16,"value":4},
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  ]
}

Answer 1

D3 automatically computes the node degree and puts it in a new attribute .weight. The weighted graph is already given by the values of the edges. The in and out degrees can be computed easily:

nodes.forEach(function(d) {
  d.inDegree = 0;
  d.outDegree = 0;
});
links.forEach(function(d) {
  nodes[d.source].outDegree += 1;
  nodes[d.target].inDegree += 1;
});