Question

附加的代码段包含official d3 force graph example code的修改版本。当我立即插入图表时，一切都按预期工作。但是，如果我动态插入图形（您可以通过在演示中按Clear and Redraw来执行），则节点不会以相同的方式展开。有时他们甚至会留在svg的左上角。

我发现一个黑客是在插入图表后添加simulation.alphaTarget(1).restart()。不幸的是，这需要更长时间才能达到稳定的输出并且可能导致残余震颤（或旋转）。

如何让动态插入的图表在没有我的黑客的情况下立即在页面加载时插入图形的行为？

＆＃13;

var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height");

var color = d3.scaleOrdinal(d3.schemeCategory20);

var simulation = d3.forceSimulation()
    .force("link", d3.forceLink().id(function(d) { return d.id; }))
    .force("charge", d3.forceManyBody())
    .force("center", d3.forceCenter(width / 2, height / 2));

// I wrapped the d3.json invocation in this function
function drawGraph() {
  d3.json("https://gist.githubusercontent.com/mbostock/4062045/raw/5916d145c8c048a6e3086915a6be464467391c62/miserables.json", function(error, graph) {
    if (error) throw error;

    var link = svg.append("g")
        .attr("class", "links")
      .selectAll("line")
      .data(graph.links)
      .enter().append("line")
        .attr("stroke-width", function(d) { return Math.sqrt(d.value); });

    var node = svg.append("g")
        .attr("class", "nodes")
      .selectAll("circle")
      .data(graph.nodes)
      .enter().append("circle")
        .attr("r", 5)
        .attr("fill", function(d) { return color(d.group); })
        .call(d3.drag()
            .on("start", dragstarted)
            .on("drag", dragged)
            .on("end", dragended));

    node.append("title")
        .text(function(d) { return d.id; });

    simulation
        .nodes(graph.nodes)
        .on("tick", ticked);

    simulation.force("link")
        .links(graph.links);

    function ticked() {
      link
          .attr("x1", function(d) { return d.source.x; })
          .attr("y1", function(d) { return d.source.y; })
          .attr("x2", function(d) { return d.target.x; })
          .attr("y2", function(d) { return d.target.y; });

      node
          .attr("cx", function(d) { return d.x; })
          .attr("cy", function(d) { return d.y; });
    }
  });
}

// When I call it hear, all is well (as you would expect).
drawGraph()

// But when I clear and redraw it (by pressing a button), the nodes
// don't spread out.
function clearRedraw() {
  d3.selectAll("svg > *").remove()
  drawGraph()
}

function hackySolution() {
  d3.selectAll("svg > *").remove()
  drawGraph()
  simulation.alphaTarget(1).restart()
}


function dragstarted(d) {
  if (!d3.event.active) simulation.alphaTarget(0.3).restart();
  d.fx = d.x;
  d.fy = d.y;
}

function dragged(d) {
  d.fx = d3.event.x;
  d.fy = d3.event.y;
}

function dragended(d) {
  if (!d3.event.active) simulation.alphaTarget(0);
  d.fx = null;
  d.fy = null;
}

＆＃13;

.links line {
  stroke: #999;
  stroke-opacity: 0.6;
}

.nodes circle {
  stroke: #fff;
  stroke-width: 1.5px;
}

＆＃13;

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body>
  <button onclick="clearRedraw()">Clear And Redraw</button>
  <button onclick="hackySolution()">Hacky Solution</button>
  <svg width="960" height="600"></svg>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/4.2.3/d3.min.js"></script>
</body>
</html>

＆＃13;

Answer 1

不一个hacky解决方案！这是重新加热模拟的正确，惯用方法。

这里的问题是，当你这样做时......

d3.selectAll("svg > *").remove()

...您只是删除了DOM元素。然而，模拟仍然在运行，并且已经冷却下来。

实际上，如果你等到模拟完全结束（大约5秒钟）才点击＆＃34;清除和重绘＆＃34;，你就会发现节点总是堆积在原点（左上角）。尝试点击它们：它们将移动到中心（因为拖动功能可以重新加热模拟，因为它具有alphaTarget）。

因此，你必须重新加热它。

但是，您应该使用alphaTarget：

，而不是使用alpha

simulation.alpha(0.8).restart()

以下是具有该更改的代码：

＆＃13;

var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height");

var color = d3.scaleOrdinal(d3.schemeCategory20);

var simulation = d3.forceSimulation()
    .force("link", d3.forceLink().id(function(d) { return d.id; }))
    .force("charge", d3.forceManyBody())
    .force("center", d3.forceCenter(width / 2, height / 2));

// I wrapped the d3.json invocation in this function
function drawGraph() {
  d3.json("https://gist.githubusercontent.com/mbostock/4062045/raw/5916d145c8c048a6e3086915a6be464467391c62/miserables.json", function(error, graph) {
    if (error) throw error;

    var link = svg.append("g")
        .attr("class", "links")
      .selectAll("line")
      .data(graph.links)
      .enter().append("line")
        .attr("stroke-width", function(d) { return Math.sqrt(d.value); });

    var node = svg.append("g")
        .attr("class", "nodes")
      .selectAll("circle")
      .data(graph.nodes)
      .enter().append("circle")
        .attr("r", 5)
        .attr("fill", function(d) { return color(d.group); })
        .call(d3.drag()
            .on("start", dragstarted)
            .on("drag", dragged)
            .on("end", dragended));

    node.append("title")
        .text(function(d) { return d.id; });

    simulation
        .nodes(graph.nodes)
        .on("tick", ticked);

    simulation.force("link")
        .links(graph.links);

    function ticked() {
      link
          .attr("x1", function(d) { return d.source.x; })
          .attr("y1", function(d) { return d.source.y; })
          .attr("x2", function(d) { return d.target.x; })
          .attr("y2", function(d) { return d.target.y; });

      node
          .attr("cx", function(d) { return d.x; })
          .attr("cy", function(d) { return d.y; });
    }
  });
}

// When I call it hear, all is well (as you would expect).
drawGraph()

// But when I clear and redraw it (by pressing a button), the nodes
// don't spread out.
function clearRedraw() {
  d3.selectAll("svg > *").remove()
  drawGraph()
}

function hackySolution() {
  d3.selectAll("svg > *").remove()
  drawGraph()
  simulation.alpha(0.8).restart()
}


function dragstarted(d) {
  if (!d3.event.active) simulation.alphaTarget(0.3).restart();
  d.fx = d.x;
  d.fy = d.y;
}

function dragged(d) {
  d.fx = d3.event.x;
  d.fy = d3.event.y;
}

function dragended(d) {
  if (!d3.event.active) simulation.alphaTarget(0);
  d.fx = null;
  d.fy = null;
}

＆＃13;

.links line {
  stroke: #999;
  stroke-opacity: 0.6;
}

.nodes circle {
  stroke: #fff;
  stroke-width: 1.5px;
}

＆＃13;

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body>
  <button onclick="clearRedraw()">Clear And Redraw</button>
  <button onclick="hackySolution()">Hacky Solution</button>
  <svg width="960" height="600"></svg>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/4.2.3/d3.min.js"></script>
</body>
</html>

＆＃13;

或者，如果你仍然认为重新加热模拟是一个hacky解决方案（它不是），只需将模拟任务移到drawGraph函数内部：

＆＃13;

var svg = d3.select("svg"),
  width = +svg.attr("width"),
  height = +svg.attr("height");

var color = d3.scaleOrdinal(d3.schemeCategory20);



// I wrapped the d3.json invocation in this function
function drawGraph() {
  d3.json("https://gist.githubusercontent.com/mbostock/4062045/raw/5916d145c8c048a6e3086915a6be464467391c62/miserables.json", function(error, graph) {
    if (error) throw error;

    var simulation = d3.forceSimulation()
      .force("link", d3.forceLink().id(function(d) {
        return d.id;
      }))
      .force("charge", d3.forceManyBody())
      .force("center", d3.forceCenter(width / 2, height / 2));

    var link = svg.append("g")
      .attr("class", "links")
      .selectAll("line")
      .data(graph.links)
      .enter().append("line")
      .attr("stroke-width", function(d) {
        return Math.sqrt(d.value);
      });

    var node = svg.append("g")
      .attr("class", "nodes")
      .selectAll("circle")
      .data(graph.nodes)
      .enter().append("circle")
      .attr("r", 5)
      .attr("fill", function(d) {
        return color(d.group);
      })
      .call(d3.drag()
        .on("start", dragstarted)
        .on("drag", dragged)
        .on("end", dragended));

    node.append("title")
      .text(function(d) {
        return d.id;
      });

    simulation
      .nodes(graph.nodes)
      .on("tick", ticked);

    simulation.force("link")
      .links(graph.links);

    function ticked() {
      link
        .attr("x1", function(d) {
          return d.source.x;
        })
        .attr("y1", function(d) {
          return d.source.y;
        })
        .attr("x2", function(d) {
          return d.target.x;
        })
        .attr("y2", function(d) {
          return d.target.y;
        });

      node
        .attr("cx", function(d) {
          return d.x;
        })
        .attr("cy", function(d) {
          return d.y;
        });
    }
  });
}

// When I call it hear, all is well (as you would expect).
drawGraph()

// But when I clear and redraw it (by pressing a button), the nodes
// don't spread out.
function clearRedraw() {
  d3.selectAll("svg > *").remove()
  drawGraph()
}


function dragstarted(d) {
  if (!d3.event.active) simulation.alphaTarget(0.3).restart();
  d.fx = d.x;
  d.fy = d.y;
}

function dragged(d) {
  d.fx = d3.event.x;
  d.fy = d3.event.y;
}

function dragended(d) {
  if (!d3.event.active) simulation.alphaTarget(0);
  d.fx = null;
  d.fy = null;
}

＆＃13;

.links line {
  stroke: #999;
  stroke-opacity: 0.6;
}

.nodes circle {
  stroke: #fff;
  stroke-width: 1.5px;
}

＆＃13;

<button onclick="clearRedraw()">Clear And Redraw</button>
<svg width="960" height="600"></svg>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/4.2.3/d3.min.js"></script>

＆＃13;

动态插入的d3力图未展开

1 个答案: