📌  相关文章
📜  networkx 探索节点 - Javascript (1)

📅  最后修改于: 2023-12-03 15:33:06.222000             🧑  作者: Mango

Networkx Exploring Nodes - Javascript

Introduction

In network analysis, exploring nodes is the most basic and important task. One popular library in Python for network analysis is Networkx. However, sometimes we want to do network analysis in Javascript environment. In this article, we will explore how we can explore nodes in network using Javascript.

Network Graph Data

To explore nodes in a network, we first need to represent the network graph data. There are many ways to represent a network graph, but one popular and easy way is to use an edge list. The edge list is just a list of pairs of nodes that are connected by edges. Here is an example of an edge list data:

[
  ["Node 1", "Node 2"],
  ["Node 1", "Node 3"],
  ["Node 2", "Node 3"],
  ["Node 2", "Node 4"],
  ["Node 3", "Node 4"]
]

Creating Network Graph in Javascript

To create a network graph in Javascript, we can use the D3.js library. D3.js is a popular library for data visualization and it also provides functionalities to create network graphs. Here is an example code to create a network graph using D3.js:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <script src="https://d3js.org/d3.v6.min.js"></script>
  </head>
  <body>
    <svg width="500" height="500"></svg>
    <script>
      const data = [
        ["Node 1", "Node 2"],
        ["Node 1", "Node 3"],
        ["Node 2", "Node 3"],
        ["Node 2", "Node 4"],
        ["Node 3", "Node 4"]
      ];
      
      const links = data.map(d => Object.create({source: d[0], target: d[1]}));
      const nodes = [...new Set(data.flat())].map(d => Object.create({id: d}));

      const simulation = d3.forceSimulation(nodes)
          .force("link", d3.forceLink().links(links))
          .force("charge", d3.forceManyBody().strength(-100))
          .force("center", d3.forceCenter(250, 250))
          .on("tick", ticked);

      const svg = d3.select("svg");
      const link = svg.selectAll(".link");
      const node = svg.selectAll(".node");

      function ticked() {
        link.attr("x1", d => d.source.x)
            .attr("y1", d => d.source.y)
            .attr("x2", d => d.target.x)
            .attr("y2", d => d.target.y);

        node.attr("cx", d => d.x)
            .attr("cy", d => d.y)
            .attr("r", 5);
      }

      link.data(links)
          .enter().append("line")
          .attr("class", "link")
          .style("stroke", "#ccc");

      node.data(nodes)
          .enter().append("circle")
          .attr("class", "node")
          .attr("r", 5)
          .style("fill", "#69b3a2")
          .call(drag(simulation));

      function drag(simulation) {

        function dragstarted(event, d) {
          if (!event.active) simulation.alphaTarget(0.3).restart();
          d.fx = d.x;
          d.fy = d.y;
        }

        function dragged(event, d) {
          d.fx = event.x;
          d.fy = event.y;
        }

        function dragended(event, d) {
          if (!event.active) simulation.alphaTarget(0);
          d.fx = null;
          d.fy = null;
        }

        return d3.drag()
            .on("start", dragstarted)
            .on("drag", dragged)
            .on("end", dragended);
      }
    </script>
  </body>
</html>

Exploring Nodes in Network

Once we have the network graph created, we can explore the nodes in network by simply interacting with the nodes using mouse events. Here is an example code to add mouse events to nodes and print the node id to console when clicking the node:

const svg = d3.select("svg");
const link = svg.selectAll(".link");
const node = svg.selectAll(".node");

function ticked() {
  link.attr("x1", d => d.source.x)
      .attr("y1", d => d.source.y)
      .attr("x2", d => d.target.x)
      .attr("y2", d => d.target.y);

  node.attr("cx", d => d.x)
      .attr("cy", d => d.y)
      .attr("r", 5)
      .on("click", function(event, d) {
        console.log(d.id);
      });
}

Conclusion

In this article, we have learned how to explore nodes in network using Javascript and D3.js library. We have created a network graph from edge list data, explored the nodes in network using mouse events, and printed the node id to console when clicking the node. The code snippets provided here can be used as a starting point to create more complex network analysis in Javascript environment.