我希望使用d3js作为此http://bl.ocks.org/d3noob/8375092来创建可折叠图形，但是我想添加许多根点（在下面的示例中为Top Level_1和Top Level_2）
var treeData = [
{
"name": "Top Level_1",
"parent": "null",
"children": [
{
"name": "Level 2: A",
"parent": "Top Level",
"children": [
{
"name": "Son of A",
"parent": "Level 2: A"
},
{
"name": "Daughter of A",
"parent": "Level 2: A"
}
]
},
{
"name": "Level 2: B",
"parent": "Top Level"
}
],
"name": "Top Level_2",
"parent": "null",
"children": [
{
"name": "Level 2_2: A",
"parent": "Top Level",
"children": [
{
"name": "Son of A_2",
"parent": "Level 2_2: A"
},
{
"name": "Daughter of A_2",
"parent": "Level 2_2: A"
}
]
},
{
"name": "Level 2_2: B",
"parent": "Top Level_2"
}
]
}
];
此示例不起作用。怎么可能在同一张图中创建许多单独的可折叠树？
答案 0 :(得分：1)
层级图只能有一个根。曾经有人要求d3允许多根树，但是到目前为止，所有这些都被拒绝了。要创建具有多个根的树，我们可以创建两个单独的树，也可以通过隐藏根节点来伪造具有两个单独的树。
您的数据结构无效（使用代码格式化程序标准化缩进是一个好主意，以确保您不会对像这样的复杂数据结构产生错误），因此我添加了一个根节点并编辑了现有节点正确表示层次结构。
隐藏根节点的最简单方法是使用CSS。为此，我根据其在树中的深度（例如level-n，level-0等）为每个节点，链接和文本项提供了一个类level-1。然后，隐藏根和来自根的链接就是将类level-0的元素设置为具有opacity: 0的问题。
使用d3noob collapsible tree中的代码，我们可以找到update函数代码的相关部分，并添加新的CSS类：
// add the class to the whole `g` element
var nodeEnter = node.enter().append("g")
.attr("class", function(d){
return 'node level-'+d.depth; // add the node depth
})
.attr("transform", function(d) { return "translate(" + source.y0 + "," + source.x0 + ")"; })
.on("click", click);
对链接执行相同的操作
// each link has two nodes, the source and the target; we want to
// label our links with the source node (the parent node)
link.enter().insert("path", "g")
.attr("class", function(d){
return 'link level-' + d.source.depth})
.attr("d", function(d) {
var o = {x: source.x0, y: source.y0};
return diagonal({source: o, target: o});
});
在CSS页面中，将css类level-0设置为不透明度0：
.level-0 {
opacity: 0;
}
由于我们现在左边缺少节点的地方有一个空白空间，因此整个图表都可以移到左侧。您可能需要相应地更改树的尺寸。
代码现在看起来像这样：
var treeData = [{
name: "null",
children: [{
"name": "Top Level_1",
"parent": "null",
"children": [{
"name": "Level 2: A",
"parent": "Top Level_1",
"children": [{
"name": "Son of A",
"parent": "Level 2: A"
}, {
"name": "Daughter of A",
"parent": "Level 2: A"
}]
},
{
"name": "Level 2: B",
"parent": "Top Level"
}],
}, {
"name": "Top Level_2",
"parent": "null",
"children": [
{
"name": "Level 2_2: A",
"parent": "Top Level_2",
"children": [
{
"name": "Son of A_2",
"parent": "Level 2_2: A"
},
{
"name": "Daughter of A_2",
"parent": "Level 2_2: A"
}]
},
{
"name": "Level 2_2: B",
"parent": "Top Level_2"
}]
}]
}];
// ************** Generate the tree diagram *****************
var margin = {
top: 20,
right: 120,
bottom: 20,
left: 120
},
width = 960 - margin.right - margin.left,
height = 500 - margin.top - margin.bottom;
var i = 0,
duration = 750,
root;
var tree = d3.layout.tree()
.size([height, width]);
var diagonal = d3.svg.diagonal()
.projection(function(d) {
return [d.y, d.x];
});
var svg = d3.select("body").append("svg")
.attr("width", width + margin.right + margin.left)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + (margin.left - 120) + "," + margin.top + ")");
root = treeData[0];
root.x0 = height / 2;
root.y0 = 0;
update(root);
d3.select(self.frameElement).style("height", "500px");
function update(source) {
// Compute the new tree layout.
var nodes = tree.nodes(root).reverse(),
links = tree.links(nodes);
// Normalize for fixed-depth.
nodes.forEach(function(d) {
d.y = d.depth * 120;
});
// Update the nodes…
var node = svg.selectAll("g.node")
.data(nodes, function(d) {
return d.id || (d.id = ++i);
});
// Enter any new nodes at the parent's previous position.
var nodeEnter = node.enter().append("g")
.attr("class", function(d) {
return 'node level-' + d.depth;
})
.attr("transform", function(d) {
return "translate(" + source.y0 + "," + source.x0 + ")";
})
.on("click", click);
nodeEnter.append("circle")
.attr("r", 1e-6)
.style("fill", function(d) {
return d._children ? "lightsteelblue" : "#fff";
});
nodeEnter.append("text")
.attr('class', function(d) {
return 'node-text level-' + d.level
})
.attr("x", function(d) {
return d.children || d._children ? -13 : 13;
})
.attr("dy", ".35em")
.attr("text-anchor", function(d) {
return d.children || d._children ? "end" : "start";
})
.text(function(d) {
return d.name;
})
.style("fill-opacity", 1e-6);
// Transition nodes to their new position.
var nodeUpdate = node.transition()
.duration(duration)
.attr("transform", function(d) {
return "translate(" + d.y + "," + d.x + ")";
});
nodeUpdate.select("circle")
.attr("r", 10)
.style("fill", function(d) {
return d._children ? "lightsteelblue" : "#fff";
});
nodeUpdate.select("text")
.style("fill-opacity", 1);
// Transition exiting nodes to the parent's new position.
var nodeExit = node.exit().transition()
.duration(duration)
.attr("transform", function(d) {
return "translate(" + source.y + "," + source.x + ")";
})
.remove();
nodeExit.select("circle")
.attr("r", 1e-6);
nodeExit.select("text")
.style("fill-opacity", 1e-6);
// Update the links…
var link = svg.selectAll("path.link")
.data(links, function(d) {
return d.target.id;
});
// Enter any new links at the parent's previous position.
link.enter().insert("path", "g")
.attr("class", function(d) {
return 'link level-' + d.source.depth
})
.attr("d", function(d) {
var o = {
x: source.x0,
y: source.y0
};
return diagonal({
source: o,
target: o
});
});
// Transition links to their new position.
link.transition()
.duration(duration)
.attr("d", diagonal);
// Transition exiting nodes to the parent's new position.
link.exit().transition()
.duration(duration)
.attr("d", function(d) {
var o = {
x: source.x,
y: source.y
};
return diagonal({
source: o,
target: o
});
})
.remove();
// Stash the old positions for transition.
nodes.forEach(function(d) {
d.x0 = d.x;
d.y0 = d.y;
});
}
// 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);
}