How to display a text when mouseover a node in D3 force layout

StackOverflow https://stackoverflow.com/questions/23584748

Question

I am trying to display the text when I move the mouse over a node in Force-Directed Graph in D3.js. My problem is that when I move the mouse over any node, all the texts of these nodes are displayed. Here is my code: 

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

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

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

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

node .text {
font: 12px sans-serif;
pointer-events: none;
}

</style>
</head>
<body>
<script src="http://d3js.org/d3.v3.js"></script>
<script src="d3/d3.v3.min.js charset=UTF-8"></script>
<script>
var graph = {
"nodes":[
{"name":"Myriel","group":1},
{"name":"Napoleon","group":1},
{"name":"Mlle.Baptistine","group":1},
{"name":"Mme.Magloire","group":1},
{"name":"CountessdeLo","group":1}
],
"links":[
{"source":1,"target":0,"value":1},
{"source":2,"target":0,"value":8},
{"source":3,"target":0,"value":10},
{"source":3,"target":2,"value":6},
{"source":4,"target":0,"value":1}
]
};
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 drawGraph = function(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 gnodes = svg.selectAll('g.gnode')//('g.gnode')
 .data(graph.nodes)
 .enter()
 .append('g')
 .classed('gnode', true);

var node = gnodes.append("circle")
  .attr("class", "node")
  .attr("r", 5)
  .style("fill", function(d) { return color(d.group); })
  .on("mouseover", function(d)
 {
    d3.select(this).transition()
    .duration(750)
    .attr("r", 15);
    return labels.style("visibility", "visible");
 })
.on("mouseout", function()
 {
 d3.select(this).transition()
.duration(750)
.attr("r", 5);
 return labels.style("visibility", "hidden");//})
 })
 .call(force.drag);

 var labels = gnodes.append("text")
  .text(function(d) { return d.name; })
  .style("visibility", "hidden");

 /*gnodes.append("text")
 .text(function(d) { return d.name; })
 .style("visibility", "hidden");*/

 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; });

 gnodes.attr("transform", function(d) { 
    return 'translate(' + [d.x, d.y] + ')'; 
}); 
});
};

drawGraph(graph);
</script>
</body>
</html>

I tried to do the following codes but it did not work neither: 

.on("mouseover", function(d)
 {
    d3.select(this).transition()
    .duration(750)
    .attr("r", 15);
     d3.select(this).append(text)
    .style("visibility", "visible");
 })

How can I display the text that is related to a particular node when I move the mouse over that node? Could anyone please help me solve this problem. Thank you in advance.

Was it helpful?

Solution

This should help:

.on("mouseover", function(d)
 {
     d3.select(labels[0][d.index]).style("visibility","visible")
 })
.on("mouseout", function(d)
 {
     d3.select(labels[0][d.index]).style("visibility","hidden")
 })

OTHER TIPS

Learning d3 myself here - also thanks very much to juvian

I find a more transparent way of coding this would be to say 

.on("mouseover", function(d) { 
  d3.select(this).select("text").style("visibility", "visible") 
})

which selects the object you hover over (a group), selects the text inside it and changes the style to visible. This also avoids the need to make a labels variable which gets a bit messy with the array indexing.

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