使用d3.js从JSON文件读取数据

时间：2016-02-03 10:07:51

标签： javascript json d3.js

我是d3.js的新手，我正在尝试重现this tutorial中的示例B is for breaking links。

正如您在本示例的jsfiddle中看到的那样，数据是从<script type="application/json" id="mis">标签中读取的，但我想要的是从不同的文件中读取数据。

我按照Force-Layout example中的建议使用了d3.json()函数，但是当我添加了应该打破链接的阈值滑块时，没有任何反应。

当我运行控制台时，它给了我以下错误：

Uncaught TypeError: Cannot read property 'splice' of 
undefined
threshold @ index.html:82
onchange @ index.html:101

这是我的代码：

output.json

文件output.json位于this link。

的index.html 

<!DOCTYPE html>
<meta charset="utf-8">
<style>

.node {
  stroke: #fff;
  stroke-width: 1.5px;
}

.link {
  stroke: #999;
  stroke-opacity: .6;
}

h3 {
    color: #1ABC9C;
    text-align:center;  
    font-style: italic;
    font-size: 14px;
    font-family: "Helvetica";
}

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>

var width = 960,
    height = 500;

var color = d3.scale.category20();

var force = d3.layout.force()
    .charge(-120)
    .linkDistance(30)
    .size([width, height]);

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

var graph = d3.json("output.json", function(error, graph) {
  if (error) throw error;

  graphRec=JSON.parse(JSON.stringify(graph));

  force
      .nodes(graph.nodes)
      .links(graph.links)
      .start();

  var link = svg.selectAll(".link")
      .data(graph.links)
    .enter().append("line")
      .attr("class", "link")
      .style("stroke-width", function(d) { return Math.sqrt(d.value); });

  var node = svg.selectAll(".node")
      .data(graph.nodes)
    .enter().append("circle")
      .attr("class", "node")
      .attr("r", 5)
      .style("fill", function(d) { return color(d.group); })
      .call(force.drag);

  node.append("title")
      .text(function(d) { return d.name; });

  force.on("tick", function() {
    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; });
  });
});

//adjust threshold
function threshold(thresh) {
    graph.links.splice(0, graph.links.length);
        for (var i = 0; i < graphRec.links.length; i++) {
            if (graphRec.links[i].value > thresh) {graph.links.push(graphRec.links[i]);}
        }
    restart();
}
//Restart the visualisation after any node and link changes
function restart() {
    link = link.data(graph.links);
    link.exit().remove();
    link.enter().insert("line", ".node").attr("class", "link");
    node = node.data(graph.nodes);
    node.enter().insert("circle", ".cursor").attr("class", "node").attr("r", 5).call(force.drag);
    force.start();
}

</script>

<form>
    <h3> Link threshold 0 <input type="range" id="thersholdSlider" name="points" value = 0 min="0" max="10" onchange="threshold(this.value)"> 10 </h3>
</form>

我做错了什么？我该如何解决？

谢谢！

1 个答案:

答案 0 :(得分：2)

我在代码中找不到任何错误。我能找到的唯一问题是变量名称图表使用了两次。

  

var graph = d3.json（“output.json”，函数（错误，图形）{
      ---------------------
      ---------------------
  }）;

修改：试用此代码。

var graphRec, node, link;
d3.json("output.json", function(error, graph) {
   if (error) throw error;
   graph = JSON.parse(JSON.stringify(graph));

   force
      .nodes(graph.nodes)
      .links(graph.links)
      .start();

   graphRec = graph;

   link = svg.selectAll(".link")
      .data(graph.links)
      .enter().append("line")
      .attr("class", "link")
      .style("stroke-width", function(d) { return Math.sqrt(d.value); });

   node = svg.selectAll(".node")
      .data(graph.nodes)
      .enter().append("circle")
      .attr("class", "node")
      .attr("r", 5)
      .style("fill", function(d) { return color(d.group); })
      .call(force.drag);

   ------------------------
   ------------------------
});

//adjust threshold
function threshold(thresh) {
    graphRec.links.splice(0, graphRec.links.length);
        for (var i = 0; i < graphRec.links.length; i++) {
            if (graphRec.links[i].value > thresh) {graphRec.links.push(graphRec.links[i]);}
        }
    restart();
}
//Restart the visualisation after any node and link changes
function restart() {
    link = link.data(graphRec.links);
    link.exit().remove();
    link.enter().insert("line", ".node").attr("class", "link");
    node = node.data(graphRec.nodes);
    node.enter().insert("circle", ".cursor").attr("class", "node").attr("r", 5).call(force.drag);
    force.start();
}

工作代码段。

var width = 960,
  height = 500;

var color = d3.scale.category20();

var force = d3.layout.force()
  .charge(-120)
  .linkDistance(30)
  .size([width, height]);

var svg = d3.select("body").append("svg")
  .attr("width", width)
  .attr("height", height);
   
var graph = {"nodes":[{"name":"DOU,_H.","group":1},{"name":"QUONIAM","group":1},{"name":"DA_SILV","group":1},{"name":"GUIMARA","group":1},{"name":"SOARES_","group":0}],"links":[{"source":1,"target":0,"value":19,"oriented":false,"date":null},{"source":1,"target":2,"value":2,"oriented":false,"date":null},{"source":1,"target":3,"value":1,"oriented":false,"date":null},{"source":1,"target":4,"value":1,"oriented":false,"date":null},{"source":1,"target":3,"value":2,"oriented":false,"date":null}]};

  graph = JSON.parse(JSON.stringify(graph));

  force
    .nodes(graph.nodes)
    .links(graph.links)
    .start();

  graphRec = graph;

  var link = svg.selectAll(".link")
    .data(graph.links)
    .enter().append("line")
    .attr("class", "link")
    .style("stroke-width", function(d) {
      return Math.sqrt(d.value);
    });

  var node = svg.selectAll(".node")
    .data(graph.nodes)
    .enter().append("circle")
    .attr("class", "node")
    .attr("r", 5)
    .style("fill", function(d) {
      return color(d.group);
    })
    .call(force.drag);

  node.append("title")
    .text(function(d) {
      return d.name;
    });

  force.on("tick", function() {
    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;
      });
  
});

//adjust threshold
function threshold(thresh) {
    graph.links.splice(0, graph.links.length);
    for (var i = 0; i < graphRec.links.length; i++) {
      if (graphRec.links[i].value > thresh) {
        graph.links.push(graphRec.links[i]);
      }
    }
    restart();
  }
  //Restart the visualisation after any node and link changes

function restart() {
  link = link.data(graph.links);
  link.exit().remove();
  link.enter().insert("line", ".node").attr("class", "link");
  node = node.data(graph.nodes);
  node.enter().insert("circle", ".cursor").attr("class", "node").attr("r", 5).call(force.drag);
  force.start();
}
.node {
  stroke: #fff;
  stroke-width: 1.5px;
}

.link {
  stroke: #999;
  stroke-opacity: .6;
}

h3 {
    color: #1ABC9C;
    text-align:center;  
    font-style: italic;
    font-size: 14px;
    font-family: "Helvetica";
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>
<form>
    <h3> Link threshold 0 <input type="range" id="thersholdSlider" name="points" value = 0 min="0" max="10" onchange="threshold(this.value)"> 10 </h3>
</form>

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