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Applying Filtering

Our first node-link diagram looked quite cluttered.

There were many nodes with only one or two connections, but we're more interested in the nodes with more conenctions, so let's apply some filtering.


{
  "data": [
    {
      "name": "data",
      "url": "/data/blogs/network.csv",
      "format": {"type": "csv"}
    }
  ],

  "networks": [
    {
      "name": "network",
      "links": "data",
      "directed": true,
      "source_node": [ "id", "source" ],
      "target_node": [ "id",  "target" ],

We apply two transforms, to calculate the degree of every node, and then remove any node with a degree of 2 or less.


      "transform": [
        {"type": "metric", "metric": "degree"}
        {"type": "filterNodes", "expression": "datum.degree > 2 "}
      ]
    }


  ],

  "layouts": [
    {
      "name": "layout",
      "network": "network",
      "type": "d3-force"
    }
  ],

  "vis": [
    {
      "entries": "network.links",
      "layout": "layout",
      "mark": {
        "type": "linkpath",
        "start": "source",
        "end": "target"
      }
    },
    {
      "entries": "network.nodes",
      "layout": "layout",
      "mark": {
        "type": "circle",
        "area": 70,
        "fill": "steelblue"
      }
    }
  ]
}