在 D3 中树的链接中插入文本

Question

var treeData = [
{
"name": "glucose_tol",
"directions": ">",
"thresholds": "126",
"exits": 0.0,
"children": [
{
"name": "age",
"directions": ">",
"thresholds": "29",
"exits": 1.0,
"children": [
{
"name": true
},
{
"name": "mass_index",
"directions": ">",
"thresholds": "29.7",
"exits": 0.5,
"children": [
{
"name": true
},
{
"name": false
}
]
}
]
},
{
"name": false
}
]
},
];
// ************** 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;
var tree = d3.layout.tree()
.size([height, width]);
var diagonal = d3.svg.diagonal()
.projection(function(d) { return [d.x, d.y]; });
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 + "," + margin.top + ")");
root = treeData[0];
update(root);
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; });
// Declare the nodes…
var node = svg.selectAll("g.node")
.data(nodes, function(d) { return d.id || (d.id = ++i); });
// Enter the nodes.
var nodeEnter = node.enter().append("g")
.attr("class", "node")
.attr("transform", function(d) { 
return "translate(" + d.x + "," + d.y + ")"; });
nodeEnter.append("circle")
.attr("r", 10)
.style("fill", "#fff");
nodeEnter.append("text")
.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", 1);
// Declare the links…
var link = svg.selectAll("path.link")
.data(links, function(d) { return d.target.id; });
// Enter the links.
link.enter().insert("path", "g")
.attr("class", "link")
.attr("d", diagonal);
// Add threshold and directions
link.enter().insert("text")
.attr("font-family", "Arial, Helvetica, sans-serif")
.attr("fill", "Black")
.style("font", "normal 12px Arial")
.attr("transform", function(d) {
return "translate(" +
((d.source.x + d.target.x)/2) + "," +
((d.source.y + d.target.y)/2) + ")";
})
.attr("dy", ".35em")
.attr("text-anchor", "middle")
.text(function(d) {
//check whether thresholds is not undefined && that target.thresholds is not undefined as it will print on both sides
if (d.source.thresholds !== undefined)
if(d.target.thresholds !== undefined)
return d.source.thresholds + ' ' + d.source.directions;
})
}

.node circle {
fill: #fff;
stroke: steelblue;
stroke-width: 3px;
}
.node text { font: 12px sans-serif; }
.link {
fill: none;
stroke: #ccc;
stroke-width: 2px;
}

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

我在树的链接中间添加文本时遇到问题，因为树的最后一层没有给我任何文本。这是我必须在链接中添加文本的代码：

// Add threshold and directions
link.enter().insert("text")
.attr("font-family", "Arial, Helvetica, sans-serif")
.attr("fill", "Black")
.style("font", "normal 12px Arial")
.attr("transform", function(d) {
return "translate(" +
((d.source.x + d.target.x)/2) + "," +
((d.source.y + d.target.y)/2) + ")";
})
.attr("dy", ".35em")
.attr("text-anchor", "middle")
.text(function(d) {
//check whether thresholds is not undefined && that target.thresholds is not undefined as it will print on both sides
if (d.source.thresholds !== undefined)
if(d.target.thresholds !== undefined)
return d.source.thresholds + ' ' + d.source.directions;
})

如果我评论这两行：if (d.source.thresholds !== undefined)和if(d.target.thresholds !== undefined)，那么我会得到所有链接上的文本，但在两侧，我不想要。我如何仅在一侧获取文本，但也在最后一层获取文本。

Answer 1

首先，您需要有一种方法来找出当前节点是否在最后一个级别，或者它下面是否有更多级别。为此，我们将实现一个maxDepth变量，该变量将存储所有节点的最大值depth属性。这是在update(root)函数中完成的：

// Normalize for fixed-depth.
var maxDepth = 0;
nodes.forEach(function(d) { d.y = d.depth * 120; maxDepth = (d.depth>maxDepth)?d.depth:maxDepth;});

接下来，我们将向第二个if语句添加两个额外的检查，如下所示：

if(d.target.thresholds !== undefined || d.target.name === true && d.target.depth == maxDepth)

它将确保仅在最后一个级别将文本添加到节点true。

var treeData = [
{
"name": "glucose_tol",
"directions": ">",
"thresholds": "126",
"exits": 0.0,
"children": [
{
"name": "age",
"directions": ">",
"thresholds": "29",
"exits": 1.0,
"children": [
{
"name": true
},
{
"name": "mass_index",
"directions": ">",
"thresholds": "29.7",
"exits": 0.5,
"children": [
{
"name": true
},
{
"name": false
}
]
}
]
},
{
"name": false
}
]
},
];
// ************** 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;
var tree = d3.layout.tree()
.size([height, width]);
var diagonal = d3.svg.diagonal()
.projection(function(d) { return [d.x, d.y]; });
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 + "," + margin.top + ")");
root = treeData[0];
update(root);
function update(source) {
// Compute the new tree layout.
var nodes = tree.nodes(root).reverse(),
links = tree.links(nodes);
// Normalize for fixed-depth.
var maxDepth = 0;
nodes.forEach(function(d) { d.y = d.depth * 120; maxDepth = (d.depth>maxDepth)?d.depth:maxDepth;});
// Declare the nodes.
var node = svg.selectAll("g.node")
.data(nodes, function(d) { return d.id || (d.id = ++i); });
// Enter the nodes.
var nodeEnter = node.enter().append("g")
.attr("class", "node")
.attr("transform", function(d) { 
return "translate(" + d.x + "," + d.y + ")"; });
nodeEnter.append("circle")
.attr("r", 10)
.style("fill", "#fff");
nodeEnter.append("text")
.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", 1);
// Declare the links…
var link = svg.selectAll("path.link")
.data(links, function(d) { return d.target.id; });
// Enter the links.
link.enter().insert("path", "g")
.attr("class", "link")
.attr("d", diagonal);
// Add threshold and directions
link.enter().insert("text")
.attr("font-family", "Arial, Helvetica, sans-serif")
.attr("fill", "Black")
.style("font", "normal 12px Arial")
.attr("transform", function(d) {
return "translate(" +
((d.source.x + d.target.x)/2) + "," +
((d.source.y + d.target.y)/2) + ")";
})
.attr("dy", ".35em")
.attr("text-anchor", "middle")
.text(function(d) {
//check whether thresholds is not undefined && that target.thresholds is not undefined as it will print on both sides
if (d.source.thresholds !== undefined)
if(d.target.thresholds !== undefined || d.target.name === true && d.target.depth == maxDepth)
return d.source.thresholds + ' ' + d.source.directions;
})
}

.node circle {
fill: #fff;
stroke: steelblue;
stroke-width: 3px;
}
.node text { font: 12px sans-serif; }
.link {
fill: none;
stroke: #ccc;
stroke-width: 2px;
}

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