图可视化活动

// 创建SVG容器
const svg = d3.select("body").append("svg")
    .attr("width", 800)
    .attr("height", 600);

// 定义力导向图布局
const simulation = d3.forceSimulation()
    .force("link", d3.forceLink().id(d => d.id))
    .force("charge", d3.forceManyBody())
    .force("center", d3.forceCenter(400, 300));

// 加载数据
d3.json("data.json").then(data => {
    // 绘制边
    const link = svg.append("g")
        .attr("class", "links")
        .selectAll("line")
        .data(data.links)
        .enter().append("line")
        .attr("stroke-width", 2);

    // 绘制节点
    const node = svg.append("g")
        .attr("class", "nodes")
        .selectAll("circle")
        .data(data.nodes)
        .enter().append("circle")
        .attr("r", 10)
        .call(d3.drag()
            .on("start", dragStarted)
            .on("drag", dragged)
            .on("end", dragEnded));

    // 更新节点和边的位置
    simulation
        .nodes(data.nodes)
        .on("tick", ticked);
    simulation.force("link")
        .links(data.links);

    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);
    }

    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;
    }
});