前言
Gephi是一款开源免费跨平台基于JVM的复杂网络分析软件, 其主要用于各种网络和复杂系统, 特别是在处理网络关系数据这方面很有优势,下面是两个不错的例子
那么,我们拿到原始数据后, 怎么才能画出这样的图表呢？
布局文件生成
通过上面两个例子可以分析出,这类图表可以通过 sigma.js 画出来,但是插件本身并不提供预处理数据&&布局功能,所以在绘制图表的时候需要有一份数据文件来详细的表明节点名称,颜色,大小,横坐标, 纵坐标,边的起始节点,这类数据一般用 gexf(xml格式) 或者 json来表示.
生成gexf需要用到布局算法, 常见的有 Force-directed_graph_drawing 力导向算法, 算法的核心思想是节点之间产生斥力,边给两个节点提供拉力,通过多次迭代最后维持一个稳定状态，手动实现布局算法还是有一些复杂度的,好在gephi-tookit组件提供了API来处理数据, 首先在maven项目中加入gephi的仓库和依赖
<repositories>
<repository>
<id>gephi-snapshots</id>
<name>Gephi Snapshots</name>
<url>http://nexus.gephi.org/nexus/content/repositories/snapshots/</url>
</repository>
<repository>
<id>gephi-releases</id>
<name>Gephi Releases</name>
<url>http://nexus.gephi.org/nexus/content/repositories/releases/</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>org.gephi</groupId>
<artifactId>gephi-toolkit</artifactId>
<version>0.8.2</version>
</dependency>
</dependencies>
添加依赖完成之后,参考这个 slide, 根据需求构造一个有向图,并调用布局算法, 最后导出成gexf和pdf文件
ProjectController pc = Lookup.getDefault().lookup(ProjectController.class);
pc.newProject();
Workspace workspace = pc.getCurrentWorkspace();
//Generate a new random graph into a container
Container container = Lookup.getDefault().lookup(ContainerFactory.class).newContainer();
GraphModel graphModel = Lookup.getDefault().lookup(GraphController.class).getModel();
DirectedGraph graph = graphModel.getDirectedGraph();
Node n0 = graphModel.factory().newNode("n0");
n0.getNodeData().setLabel("n0");
Node n1 = graphModel.factory().newNode("n1");
n1.getNodeData().setLabel("n1");
Edge edge = graphModel.factory().newEdge(n0, n1, 1f, true);
graph.addNode(n0);
graph.addNode(n1);
graph.addEdge(edge);
for(int i = 0 ; i < 100; i++) {
Node ntmp = graphModel.factory().newNode("tmp" + i);
Edge edgetmp = graphModel.factory().newEdge(n0, ntmp, 1f, true);
graph.addNode(ntmp);
graph.addEdge(edgetmp);
}
System.out.println("Nodes: " + graph.getNodeCount());
System.out.println("Edges: " + graph.getEdgeCount());
//Layout for 15 seconds
AutoLayout autoLayout = new AutoLayout(20, TimeUnit.SECONDS);
autoLayout.setGraphModel(graphModel);
YifanHuLayout firstLayout = new YifanHuLayout(null, new StepDisplacement(1f));
ForceAtlasLayout secondLayout = new ForceAtlasLayout(null);
AutoLayout.DynamicProperty adjustBySizeProperty = AutoLayout.createDynamicProperty("forceAtlas.adjustSizes.name", Boolean.TRUE, 0.1f);//True after 10% of layout time
AutoLayout.DynamicProperty repulsionProperty = AutoLayout.createDynamicProperty("forceAtlas.repulsionStrength.name", new Double(500.), 0f);//500 for the complete period
autoLayout.addLayout(firstLayout, 0.9f);
autoLayout.addLayout(secondLayout, 0.1f, new AutoLayout.DynamicProperty[]{adjustBySizeProperty, repulsionProperty});
autoLayout.execute();
//Export pdf & gexf
ExportController ec = Lookup.getDefault().lookup(ExportController.class);
try {
File pdfFile = new File("/tmp/data.pdf");
File gexfFile = new File("/tmp/data.gexf");
pdfFile.getParentFile().mkdirs();
gexfFile.getParentFile().mkdirs();
ec.exportFile(pdfFile);
ec.exportFile(gexfFile);
} catch (IOException ex) {
ex.printStackTrace();
}
图表绘制
在得到数据文件后可以参考这个 Online Demo 来绘制图表。
参考资料
- http://gephi.github.io/
- http://www.slideshare.net/gephi/gephi-toolkit-tutorialtoolkit
- https://github.com/gephi/gephi/wiki/How-to-code-with-the-Toolkit
THE END
