Cytoscape.js - Find all common nodes and retain them

Question

I have a graph: B -> A, C -> A, C -> D where node B and node C are of the same type.

I would like to find and retain only the common nodes shared between the nodes which is node A. How do i filter and remove out the nodes C -> D while retaining the rest of the graph?

Answer 1

You can filter the graph with some handy methods:

// get node a
let node_a = cy.$('#a');

// get edges to -> b and c
let connected_edges = node_a.connectedEdges()

// get source and target nodes -> a, b and c
let connedted_nodes = connected_edges.connectedNodes()

// get target nodes -> b and c
let target_nodes = connected_edges.targets()

// Then you can remove the unwanted nodes (you may have to manage the edges too)
let removed_nodes = cy.remove(cy.nodes().not(connected_nodes)

Here is a working example:

var cy = window.cy = cytoscape({
  container: document.getElementById('cy'),

  boxSelectionEnabled: false,
  autounselectify: true,

  style: [{
      selector: 'node',
      css: {
        'content': 'data(id)',
        'text-valign': 'center',
        'text-halign': 'center',
        'height': '60px',
        'width': '60px',
        'border-color': 'black',
        'border-opacity': '1',
        'border-width': '10px'
      }
    },
    {
      selector: '$node > node',
      css: {
        'padding-top': '10px',
        'padding-left': '10px',
        'padding-bottom': '10px',
        'padding-right': '10px',
        'text-valign': 'top',
        'text-halign': 'center',
        'background-color': '#bbb'
      }
    },
    {
      selector: 'edge',
      css: {
        'target-arrow-shape': 'triangle'
      }
    },
    {
      selector: ':selected',
      css: {
        'background-color': 'black',
        'line-color': 'black',
        'target-arrow-color': 'black',
        'source-arrow-color': 'black'
      }
    }
  ],

  elements: {
    nodes: [{
        data: {
          id: 'n0'
        }
      },
      {
        data: {
          id: 'n1'
        }
      },
      {
        data: {
          id: 'n2'
        }
      },
      {
        data: {
          id: 'n3'
        }
      },
      {
        data: {
          id: 'n4'
        }
      },
      {
        data: {
          id: 'n5'
        }
      },
      {
        data: {
          id: 'n6'
        }
      },
      {
        data: {
          id: 'n7'
        }
      },
      {
        data: {
          id: 'n8'
        }
      },
      {
        data: {
          id: 'n9'
        }
      },
      {
        data: {
          id: 'n10'
        }
      },
      {
        data: {
          id: 'n11'
        }
      },
      {
        data: {
          id: 'n12'
        }
      },
      {
        data: {
          id: 'n13'
        }
      },
      {
        data: {
          id: 'n14'
        }
      },
      {
        data: {
          id: 'n15'
        }
      },
      {
        data: {
          id: 'n16'
        }
      }
    ],
    edges: [{
        data: {
          source: 'n0',
          target: 'n1'
        }
      },
      {
        data: {
          source: 'n1',
          target: 'n2'
        }
      },
      {
        data: {
          source: 'n1',
          target: 'n3'
        }
      },
      {
        data: {
          source: 'n2',
          target: 'n7'
        }
      },
      {
        data: {
          source: 'n2',
          target: 'n11'
        }
      },
      {
        data: {
          source: 'n2',
          target: 'n16'
        }
      },
      {
        data: {
          source: 'n3',
          target: 'n4'
        }
      },
      {
        data: {
          source: 'n3',
          target: 'n16'
        }
      },
      {
        data: {
          source: 'n4',
          target: 'n5'
        }
      },
      {
        data: {
          source: 'n4',
          target: 'n6'
        }
      },
      {
        data: {
          source: 'n6',
          target: 'n8'
        }
      },
      {
        data: {
          source: 'n8',
          target: 'n9'
        }
      },
      {
        data: {
          source: 'n8',
          target: 'n10'
        }
      },
      {
        data: {
          source: 'n11',
          target: 'n12'
        }
      },
      {
        data: {
          source: 'n12',
          target: 'n13'
        }
      },
      {
        data: {
          source: 'n13',
          target: 'n14'
        }
      },
      {
        data: {
          source: 'n13',
          target: 'n15'
        }
      },
    ]
  },

  layout: {
    name: 'dagre',
    padding: 5
  }
});

cy.on('click', 'node', function(event) {
  // get node a
  let node_a = event.target;

  // get edges to -> b and c
  let connected_edges = node_a.connectedEdges()

  // get source and target nodes -> a, b and c
  let connected_nodes = connected_edges.connectedNodes()

  // get target nodes -> b and c
  let target_nodes = connected_edges.targets()

  // Then you can remove the unwanted nodes
  // If you want, you can save removed_nodes to local storage and add them to the grap at a later point
  let removed_nodes = cy.remove(cy.nodes().not(connected_nodes))
  
  // You can run the layout directly on the new graph
  cy.layout({
    name: 'dagre',
    padding: 5
  }).run()
});

body {
  font: 14px helvetica neue, helvetica, arial, sans-serif;
}

#cy {
  height: 100%;
  width: 100%;
  left: 0;
  top: 0;
  float: left;
  position: absolute;
}

<html>

<head>
  <meta charset=utf-8 />
  <meta name="viewport" content="user-scalable=no, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, minimal-ui">
  <script src="https://unpkg.com/[email protected]/dist/jquery.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/cytoscape/3.2.17/cytoscape.min.js">
  </script>


  <!-- cyposcape dagre -->
  <script src="https://unpkg.com/[email protected]/dist/dagre.js"></script>
  <script src="https://cdn.rawgit.com/cytoscape/cytoscape.js-dagre/1.5.0/cytoscape-dagre.js"></script>

  <!-- cytoscape popper -->
  <script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/umd/popper.min.js"></script>
  <script src="https://cdn.jsdelivr.net/npm/[email protected]/cytoscape-popper.min.js"></script>

</head>

<body>
  <div id="cy"></div>
</body>

</html>