将文本添加到可折叠的 d3 树链接

Question

我在这里遵循这个例子：https://bl.ocks.org/d3noob/43a860bc0024792f8803bba8ca0d5ecd

在这一部分，我有：

  // Enter any new links at the parent's previous position.
  var linkEnter = link.enter().insert('path', "g")
      .attr("class", "link")
      .text(function(d) {
          console.log(d.data.expression);
          return d.data.expression;
      })
      .attr('d', function(d){
        var o = {x: source.x0, y: source.y0}
        return diagonal(o, o)
      });

我看到了控制台的输出，但在链接上看不到明显的文本。

下面是整个 update(( 方法。

function update(source) {
  // Assigns the x and y position for the nodes
  var treeData = treemap(root);
  // Compute the new tree layout.
  var nodes = treeData.descendants(),
      links = treeData.descendants().slice(1);
  // Normalize for fixed-depth.
  nodes.forEach(function(d){ d.y = d.depth * 180});
  // ****************** Nodes section ***************************
  // Update the nodes...
  var node = svg.selectAll('g.node')
      .data(nodes, function(d) {return d.id || (d.id = ++i); });
  // Enter any new modes at the parent's previous position.
  var nodeEnter = node.enter().append('g')
      .attr('class', 'node')
      .attr("transform", function(d) {
        return "translate(" + source.y0 + "," + source.x0 + ")";
    })
    .on('click', click);
  // Add Circle for the nodes
  nodeEnter.append('circle')
      .attr('class', 'node')
      .attr('r', 1e-6)
      .style("fill", function(d) {
          return d._children ? "lightsteelblue" : "#fff";
      });
  // Add labels for the nodes
  nodeEnter.append('text')
      .attr("dy", ".35em")
      .attr("x", function(d) {
          return d.children || d._children ? -13 : 13;
      })
      .attr("text-anchor", function(d) {
          return d.children || d._children ? "end" : "start";
      })
      .text(function(d) { return "expression: " + d.data.expression; });
  // UPDATE
  var nodeUpdate = nodeEnter.merge(node);
  // Transition to the proper position for the node
  nodeUpdate.transition()
    .duration(duration)
    .attr("transform", function(d) {
        return "translate(" + d.y + "," + d.x + ")";
     });
  // Update the node attributes and style
  nodeUpdate.select('circle.node')
    .attr('r', 10)
    .style("fill", function(d) {
        return d._children ? "lightsteelblue" : "#fff";
    })
    .attr('cursor', 'pointer');

  // Remove any exiting nodes
  var nodeExit = node.exit().transition()
      .duration(duration)
      .attr("transform", function(d) {
          return "translate(" + source.y + "," + source.x + ")";
      })
      .remove();
  // On exit reduce the node circles size to 0
  nodeExit.select('circle')
    .attr('r', 1e-6);
  // On exit reduce the opacity of text labels
  nodeExit.select('text')
    .style('fill-opacity', 1e-6);
  // ****************** links section ***************************
  // Update the links...
  var link = svg.selectAll('path.link')
      .data(links, function(d) { return d.id; });
  // Enter any new links at the parent's previous position.
  var linkEnter = link.enter().insert('path', "g")
      .attr("class", "link")
      .text(function(d) {
          console.log(d.data.expression);
           return d.data.expression;
      })
      .attr('d', function(d){
        var o = {x: source.x0, y: source.y0}
        return diagonal(o, o)
      });
  // UPDATE
  var linkUpdate = linkEnter.merge(link);
  // Transition back to the parent element position
  linkUpdate.transition()
      .duration(duration)
      .attr('d', function(d){ return diagonal(d, d.parent) });
  // Remove any exiting links
  var linkExit = link.exit().transition()
      .duration(duration)
      .attr('d', function(d) {
        var o = {x: source.x, y: source.y}
        return diagonal(o, o)
      })
      .remove();
  // Store the old positions for transition.
  nodes.forEach(function(d){
    d.x0 = d.x;
    d.y0 = d.y;
  });
  // Creates a curved (diagonal) path from parent to the child nodes
  function diagonal(s, d) {
    path = `M ${s.y} ${s.x}
            C ${(s.y + d.y) / 2} ${s.x},
              ${(s.y + d.y) / 2} ${d.x},
              ${d.y} ${d.x}`
    return path
  }
  // Toggle children on click.
  function click(d) {
    if (d.children) {
        d._children = d.children;
        d.children = null;
      } else {
        d.children = d._children;
        d._children = null;
      }
    update(d);
  }
}

如果有人能提供一些启示，我将不胜感激。谢谢！

Answer 1

目前还不清楚你想用这条线实现什么，但问题是：

插入后...

var linkEnter = link.enter().insert('path', "g")

。此选择是<path>选择。而且，当然，设置路径的text属性(没有(是没有意义的。

无论您想要什么，都可以在两个选项中打破块：

var linkEnter = link.enter().insert('path', "g")
    .attr("class", "link")
    .attr('d', function(d) {
        var o = {
            x: source.x0,
            y: source.y0
        }
        return diagonal(o, o)
    });
var fooEnter = link.enter().insert('text', "g")
    .attr("class", "link")
    .text(function(d) {
        console.log(d.data.expression);
        return d.data.expression;
    });