CODEWITHSUNDEEP
javascripthtmld3.js
Best Jeanist
Best Jeanist

Reputation: 1129

Adding zoom function to a force directed graph

Hi I just started out using javascript and I was wondering how to add a zoom function to my graph using Mike Bostock's template. But it seems like its not as easy as I thought.

<script>

var svg = d3.select("svg"),
width = +svg.attr("width"),
height = +svg.attr("height");

var color = d3.scaleOrdinal(d3.schemeCategory20);

var simulation = d3.forceSimulation()
.force("link", d3.forceLink().id(function(d) { return d.id; }))
.force("charge", d3.forceManyBody())
.force("center", d3.forceCenter(width / 2, height / 2));

d3.json("miserables.json", function(error, graph) {
if (error) throw error;

I also have added the encompassing group for the zoom.

var g = svg.append("g")
.attr("class", "everything");


 var link = svg.append("g")
 .attr("class", "links")
 .selectAll("line")
 .data(graph.links)
 .enter().append("line")
  .attr("stroke-width", function(d) { return Math.sqrt(d.value); });

  var node = svg.append("g")
  .attr("class", "nodes")
  .selectAll("circle")
  .data(graph.nodes)
  .enter().append("circle")
  .attr("r", 5)
  .attr("fill", function(d) { return color(d.group); })
  .call(d3.drag()
      .on("start", dragstarted)
      .on("drag", dragged)
      .on("end", dragended));

 node.append("title")
  .text(function(d) { return d.id; });

I have added the zoom handler and all but there is completely no change in my graph even if I scroll.

 var zoom_handler = d3.zoom()
 .on("zoom", zoom_actions);

 zoom_handler(svg);   


 simulation
  .nodes(graph.nodes)
  .on("tick", ticked);

 simulation.force("link")
  .links(graph.links);

  function zoom_actions(){
 g.attr("transform", d3.event.transform)
 }


 function ticked() {
 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; });
  }
  });

function dragstarted(d) {
if (!d3.event.active) simulation.alphaTarget(0.3).restart();
d.fx = d.x;
d.fy = d.y;
}

function dragged(d) {
d.fx = d3.event.x;
d.fy = d3.event.y;
}

function dragended(d) {
if (!d3.event.active) simulation.alphaTarget(0);
d.fx = null;
d.fy = null;
}


</script>

Upvotes: 1

Views: 311

Answers (1)

Gerardo Furtado
Gerardo Furtado

Reputation: 102184

Your mistake here is quite simple: you set the group selection...

var g = svg.append("g")
    .attr("class", "everything");

... but you're appending the nodes and links to the SVG selection:

var link = svg.append("g")//etc...

var node = svg.append("g")//etc...

Solution: append the nodes and links to the group you created:

var link = g.append("g")//etc...

var node = g.append("g")//etc...

Here is the original bl.ocks with that change: https://bl.ocks.org/GerardoFurtado/30220ae7281145b32c9e2bf090a5ae1a/1f544def619312cc62ad39058aa6ec84efae67c7

Upvotes: 2

Related Questions