javascript - 多个力布局导致滴答函数冲突

Question

我试图同时在一个页面上放置多个 D3 强制布局。力布局的数量理想情况下是可变的，具体取决于从动态 API 返回的根数。我遵循了答案 on this question regarding multiple force layouts并已成功将每个布局放入单独的 div 和单独的 svg 中。

但是，问题是双重的:

1) svg 似乎是同时绘制的，导致 alpha 冷却参数发生冲突(在每个图形的“刻度”上)。因此，唯一按照预期方式定位的布局是页面上绘制的最后一个 svg。 tick 函数包含将力布局塑造成类似于垂柳树的代码，根节点位于顶部，子节点位于其下方。

2) 设置循环以迭代来自 API 的完整结果列表会导致 D3 崩溃，并出现错误“Uncaught TypeError: Cannot read property 'textContent' of null。”

我认为理想的解决方案是在成功渲染前一个力布局后绘制每个力布局，其方式不会导致 alpha 冷却参数(在“滴答”上)发生冲突，或者使 D3 库重载一次强制布局的实例太多。有人对这个问题有洞察力吗？这是我的代码:

/* ... GET THE RESULTS FROM THE API ...*/
function handleRequest2(json) {
        allroots = json[1]['data']['children'];
        (function() {
            var index = 0;
            function LoopThrough() {
                currentRoot = allroots[index];  
                if (index < allroots.length) {
                    /* DRAW THE GRAPH */
                    draw_graphs(currentRoot, index);  
                    ++index;
                    LoopThrough();
                    };
            }

        LoopThrough();
        })(); 

    }
//Force Layout Code
function draw_graphs(root, id) {
var root_id = "map-" + id.toString();
var force;
var vis;
var link;
var node;
var w = 980;
var h = 1000;
var k = 0;
// Create a separate div to house each SVG graph
  div = document.createElement("div");
  div.style.width = "980px";
  div.style.height = "1000px";
  div.style.cssFloat="left";
  div.id = root_id;
  $(div).addClass("chattermap-map");
  // Append the div to the chart container
  $('#chart').append(div);

force = d3.layout.force()
  .size([w, h])
  .charge(-250)
  .gravity(0)
  .on("tick", tick);
  // Create the SVG and append it to the created div
vis = d3.select("#"+root_id)
  .append("svg:svg")
  .attr("width", w)
  .attr("height", h)
  .attr("id",root_id);


  // Put the Reddit JSON in the correct format for the Force Layout
nodes = flatten(root),
links = optimize(d3.layout.tree().links(nodes));
// Calculations for the sizing of the nodes
avgNetPositive = getAvgNetPositive();
maxNetPositive = d3.max(netPositiveArray);
minNetPositive = d3.min(netPositiveArray);
// Create a logarithmic scale that sizes the nodes
radius = d3.scale.pow().exponent(.3).domain([minNetPositive,maxNetPositive]).range([5,30]);
// Fix the root node to the top of the svg
root.data.fixed = true;
root.data.x = w/2;
root.data.y = 50;
  // Start the force layout.
force
  .nodes(nodes)
  .links(links)
  .start();
  // Update the links
  link = vis.selectAll("line.link")
    .data(links, function(d) { return d.target.id; });
  // Enter any new links.
  link.enter().insert("svg:line", ".node")
    .attr("class", "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; });
  // Exit any old links.
  link.exit().remove();
  // Update the nodes
  node = vis.selectAll("circle.node")
    .data(nodes, function(d) {return d.id; })
    .style("fill", function(d) {
      return '#2960b5';
    });
    // Enter any new nodes.
  node.enter().append("svg:circle")
    .attr("class", "node")
    .attr("cx", function(d) {return d.x; })
    .attr("cy", function(d) {return d.y; })
    .attr("r", function(d) {
        //Get the net positive reaction
        var netPositive = d.ups - d.downs;
        var relativePositivity = netPositive/avgNetPositive;
        //Scale the radii based on the logarithmic scale defined earlier
        return radius(netPositive);
    })
    .style("fill", function(d) {
      return '#2960b5';
    })
    // Allow dragging on click
    .call(force.drag);
    // Exit any old nodes.
  node.exit().remove();
  //This will add the name of the author to the node HTML
  node.append("author").text(function(d) {return d.author});
  //Add the body of the comment to the node
  node.append("comment").text(function(d) {return Encoder.htmlDecode(d.body_html)}); 
  //Add the UNIX timestamp to the node
  node.append("timestamp").text(function(d) {return moment.unix(d.created_utc).fromNow();})
  //On load, assign the root node to the tooltip
  numberOfNodes = node[0].length;
  rootNode = d3.select(node[0][parseInt(numberOfNodes) - 1]);
  rootNodeComment = rootNode.select("comment").text();
  rootNodeAuthor = rootNode.select("author").text();
  rootNodeTimestamp = rootNode.select("timestamp").text();

  // Create the tooltip div for the comments
tooltip_div = d3.select("#"+root_id).append("div")
    .attr("class", "tooltip")               
      .style("opacity", 1);
//Add the HTML to the tooltip for the root
  tooltip_div .html("<span class='commentAuthor'>" + rootNodeAuthor + "</span><span class='bulletTimeAgo'>&bull;</span><span class='timestamp'>" + rootNodeTimestamp + "</span><br>" + rootNodeComment)
    //Position the tooltip based on the position of the current node, and it's size
    .style("left", (rootNode.attr("cx") - (-rootNode.attr("r")) - (-9)) + "px")   
    .style("top", (rootNode.attr("cy") - 15)  + "px");    

  node.on("mouseover", function() {
    currentNode = d3.select(this);
    currentTitle = currentNode.select("comment").text();
    currentAuthor = currentNode.select("author").text();
    currentTimestamp = currentNode.select("timestamp").text();
  tooltip_div.transition()        
     .duration(200)      
     .style("opacity", 1);
  // Add the HTML for all other tooltips on mouseover
  tooltip_div .html("<span class='commentAuthor'>" + currentAuthor + "</span><span class='bulletTimeAgo'>&bull;</span><span class='timestamp'>" + currentTimestamp + "</span><br>" + currentTitle)
              //Position the tooltip based on the position of the current node, and it's size
              .style("left", (currentNode.attr("cx") - (-currentNode.attr("r")) - (-9)) + "px")   
              .style("top", (currentNode.attr("cy") - 15)  + "px");    
   });

  // Fade out the tooltip on mouseout
  node.on("mouseout", function(d) {       
      tooltip_div.transition()        
          .duration(500)      
          .style("opacity", 1);
  });
  // Optimize the JSON output of Reddit for D3
  function flatten(root) {

    var nodes = [], i = 0, j = 0;
    function recurse(node) {

      if (node['data']['replies'] != "" && node['kind'] != "more") {
          node['data']['replies']['data']['children'].forEach(recurse);
      }
      if (node['kind'] !="more") {
          //Add an ID value to the node starting at 1
          node.data.id = ++i;
          node.data.name = node.data.body;
          //Put the replies in the key 'children' to work with the tree layout
          if (node.data.replies != "") {

               node.data.children = node.data.replies.data.children;
               //Remove the extra 'data' layer for each child
               for (j=0; j < node.data.children.length; j++) {
                  node.data.children[j] = node.data.children[j].data;
               }

          } else {
              node.data.children = "";
          }
          var comment = node.data;
          nodes.push(comment);
      }
    }
    recurse(root);
    return nodes;  
  }
  // Optimize the JSON for use with Links
  function optimize(linkArray) {
      optimizedArray = [];
      for (k=0; k < linkArray.length; k++) {
          if(typeof linkArray[k].target.count == 'undefined') {
              optimizedArray.push(linkArray[k]);
          }
      }
      return optimizedArray;
  }
  // Get the average net positive upvotes for use in sizing
  function getAvgNetPositive() {
    var sum = 0;
    netPositiveArray = []
    //Select all the nodes
    var allNodes = d3.selectAll(nodes)[0];
    //For each node, get the net positive votes and add it to the sum
    for (i=0; i < allNodes.length; i++) {
      var netPositiveEach = allNodes[i]["ups"] - allNodes[i]["downs"];
      sum += netPositiveEach;
      netPositiveArray.push(netPositiveEach);
    }
    var avgNetPositive = sum/allNodes.length;
    return avgNetPositive;
  }
  function tick(e) {
     var kx = .4 * e.alpha, ky = 1.4 * e.alpha;
     links.forEach(function(d, i) {
        d.target.x += (d.source.x - d.target.x) * kx;
        d.target.y += (d.source.y + 80 - d.target.y) * ky;
    });
    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; });
  }
  // // Remove the animation effect of the force layout
  // while ((force.alpha() > 1e-2) && (k < 150)) {
  //     force.tick(),
  //     k = k + 1;
  // }
}

提前致谢!

Answer 1

如果将多个强制布局封装在它们自己的命名空间中，例如通过单独的功能。但是，您也可以通过监听 end 事件来做您想做的事情——参见 the documentation .这样，您可以“链接”布局，在前一个布局完成后开始每个布局。

关于另一个错误，看起来这是由不完整/错误的数据引起的。