title: sankey chart is not plotting when we have source data and target data is matched tried in highcharts and d3.js
body: <p>I plotted sankey chart in D3.js and tried in highcharts too, when the data is same in source and target then the chart is not plotting. How to overcome this limitation.</p>
  
  <pre><code>    var graph = {
      "links": [
                {"source":"1","target":"1","value":"1.7"},
                {"source":"1","target":"2","value":"1.5"},
                {"source":"2","target":"3","value":"1.2"},
                {"source":"3","target":"4","value":"0.3"}
      ] ,
      "nodes": [
                {"name":"Energy"},
                {"name":"Industrial Processes"},
                {"name":"Electricity and heat"},
                {"name":"Electricity"}
      ] }
  </code></pre>
  
  <p>I tried in High Charts. I found the same problem when data is like</p>
  
  <pre><code>    series: [{
      keys: ['from', 'to', 'weight'],
      data: [{
      from: 'total',
      to: 'Useful kinetic energy',
      weight: 56,
      outgoing: true
      }, {
          from: 'total',
          to: 'total',
          weight: 27,
          outgoing: true
      }, {
          from: 'total',
          to: 'Sound loss',
          weight: 17,
          outgoing: true
      }]
  </code></pre>
  
  <p>Please suggest me how to overcome this problem, i.e when we have same data in source and target</p>