如何在 d3 上标记力导向图？

Question

我正在用 d3.js 创建一个 力导向图，但无法通过用文本标记节点的点。我在 Whosebug 和在线教程上尝试了无数答案，但我相信问题出在我的基本 Javascript 理解上。

我尝试了 .attr/.append/.text 的不同组合来显示源和目标中的文本，但没有任何反应。

这是有问题的区域：

node.append("title") .text(function (d) {return d.target}); node.append("text") .attr("dy", -3) .text(function (d) {return d.source}) .attr("class", "font");

这是样式的简化摘录：

<style> .node { fill: #ccc; /* Fill of the circles*/ stroke: #ffffff; stroke-width: 2px; } .font { font: 10px; font-family: sans-serif; } .link { stroke: #777; /* Colour of the lines*/ stroke-width: 2px; } </style>

这是脚本的简化摘录：

var width = 640, height = 480; var links = [ //this is an array {source: "Germany", target: "name1"}, {source: "Germany", target: "name2"}, {source: "Nigeria", target: "name3"}, {source: "Environment", target: "name4"}, ]; //setting up the nodes: var nodes = {}; links.forEach(function(link){ link.source = nodes[link.source] || (nodes[link.source] = {name: link.source}); link.target = nodes[link.target] || (nodes[link.target] = {name: link.target}); }); //add svg to the body, this is where the actual d3 starts var svg = d3.select("body").append("svg") .attr("width", width) .attr("height", height); var force = d3.layout.force() //Here we specify the paramaters .size([width,height]) .nodes(d3.values(nodes)) //this is where we pass the nodes of our dataset .links(links) // source of links .on("tick", tick) //on click of the nodes .linkDistance(300) //How far apart the nodes are .start(); //Start to render //add link and nodes var link = svg.selectAll(".link") .data(links) //get the data .enter().append('line') //binds the data in the links array to the svg .attr("class", "link") //css styling var node = svg.selectAll(".node") .data(force.nodes()) //way to reference the nodes in the force layout .enter().append("circle") .attr("class", "node") //attribute CSS styling .attr("r", width * 0.03); //radius of the circle //text element node.append("title") .text(function (d) {return d.target}); node.append("text") .attr("dy", -3) .text(function (d) {return d.source}) .attr("class", "font"); //creating the tick function from the force variable //the "e" paramater can be used for positioning function tick(e) { node.attr("cx", function(d) {return d.x;}) .attr("cy", function(d) {return d.y;}) .call(force.drag); //the relative location will activate a drag once the node is clicked 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; }) } </script>

我目前没有收到任何错误消息，这让我很难调试文件。任何帮助表示赞赏。谢谢！

Answer 1

你的代码有两个问题。

第一个问题是你的node选择：

var node = svg.selectAll(".node")
    .data(force.nodes())
    .enter().append("circle") 
    //etc...

如您所见，这是圈子的选择。稍后，当您尝试...

node.append("text")

... 它不会工作，因为您不能将 <text> 元素附加到 <circle> 元素。

最常见的解决方案是制作 node 组 (<g>) 选择，您可以在其中附加圆圈和文本。

第二个问题是节点的数据。你的短信里有这个：

node.append("text")
    .text(function (d) {return d.source})

但是，数据中没有名为source的属性。你唯一的属性是 name.

这是您的代码，其中包含这些更改：

var width = 640,
  height = 480;

var links = [
  //this is an array
  {
    source: "Germany",
    target: "name1"
  },
  {
    source: "Germany",
    target: "name2"
  },
  {
    source: "Nigeria",
    target: "name3"
  },
  {
    source: "Environment",
    target: "name4"
  },

];

//setting up the nodes:

var nodes = {};


links.forEach(function(link) {
  link.source = nodes[link.source] ||
    (nodes[link.source] = {
      name: link.source
    });
  link.target = nodes[link.target] ||
    (nodes[link.target] = {
      name: link.target
    });
});


//add svg to the body, this is where the actual d3 starts

var svg = d3.select("body").append("svg")
  .attr("width", width)
  .attr("height", height);

var force = d3.layout.force() //Here we specify the paramaters
  .size([width, height])
  .nodes(d3.values(nodes)) //this is where we pass the nodes of our dataset
  .links(links) // source of links
  .on("tick", tick) //on click of the nodes
  .linkDistance(300) //How far apart the nodes are
  .start(); //Start to render

//add link and nodes
var link = svg.selectAll(".link")
  .data(links) //get the data
  .enter().append('line') //binds the data in the links array to the svg 
  .attr("class", "link") //css styling

var node = svg.selectAll(".node")
  .data(force.nodes()) //way to reference the nodes in the force layout
  .enter().append("g");

node.append("circle")
  .attr("class", "node")
  .attr("r", width * 0.03); //radius of the circle

node.append("text")
  .attr("dy", -3)
  .text(function(d) {
    return d.name
  })
  .attr("class", "font");

//creating the tick function from the force variable
//the "e" paramater can be used for positioning

function tick(e) {
  node.attr("transform", function(d) {
      return "translate(" + [d.x, d.y] + ")"
    })
    .call(force.drag); //the relative location will activate a drag once the node is clicked

  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 {
  fill: #ccc;
  /* Fill of the circles*/
  stroke: #ffffff;
  stroke-width: 2px;
}

.font {
  font: 10px;
  font-family: sans-serif;

}

.link {
  stroke: #777;
  /* Colour of the lines*/
  stroke-width: 2px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.17/d3.min.js"></script>

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