Data Breaches zoom

<!DOCTYPE html>

<meta charset="utf-8">
<link href="https://fonts.googleapis.com/css?family=Merriweather" rel="stylesheet">
<style>
body {
        font-family: 'Merriweather', serif;
      }
a {
    color: white;
}
div.tooltip {
  position: absolute;
  text-align: center;
  padding: 2px;
  font: 12px sans-serif;
  background: lightsteelblue;
  border: 0px;
  border-radius: 8px;
}
</style>
<body>
  <h1>Data Breaches</h1>
<svg width="1000" height="800"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

var svg = d3.select("svg"),
    margin = {top: 60, right: 350, bottom: 110, left: 100},
    margin2 = {top: 60, right: 590, bottom: 100, left: 330},
    width = +svg.attr("width") - margin.left - margin.right,
    height = +svg.attr("height") - margin.top - margin.bottom,
    width2 = +svg.attr("width") - margin2.left - margin2.right;
 
var parseTime = d3.timeParse("%Y");
var x = d3.scaleTime().range([0, width]), 
    x2 = d3.scaleTime().range([7, width2]),
    y = d3.scaleLinear().range([1,height-10]),
    y2 = y.copy();
 
var xAxis = d3.axisTop(x),
    yAxis = d3.axisLeft(y);

var force = d3.forceManyBody()
      .strength(10);

var simulation = d3.forceSimulation()
      .force("charge", force)
  
var brush = d3.brushY()
    .extent([[0, 0], [width2, height]])
    .on("brush", brushed);
  
svg.append("defs").append("clipPath")
    .attr("id", "clip")
  	.append("rect")
    .attr("width", width)
    .attr("height", height);

var focus = svg.append("g")
    .attr("class", "focus")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var context = svg.append("g")
    .attr("class", "context")
    .attr("transform", "translate(" + 20 + "," + 58 + ")");
  
d3.csv("Data_Breaches.csv", type, function(error, data) {
  if (error) throw error;

x.domain(d3.extent(data, function(d) { return d.Year; }));
  y.domain([d3.min(data, function(d) { return d.RecordsStolen; }), d3.max(data, function(d) { return d.RecordsStolen; })]);
  x2.domain(x.domain());
  y2.domain(y.domain()); 
var div = d3.select("body").append("div")
    .attr("class", "tooltip")
    .style("opacity", 0);

// set the colour scale
  var color = d3.scaleOrdinal(d3.schemeCategory20);
// append scatter plot to main chart area 
 var dots = focus.append("g");
    dots.attr("clip-path", "url(#clip)");
    dots.selectAll("dot") 
        .data(data)
        .enter()
      	.append("circle")
        .attr('class', 'dot')
        .attr("r",3)
        .style("opacity", .7)
        .attr("cx", function(d) { return x(d.Year); })
        .attr("cy", function(d) { return y(d.RecordsStolen); })
      .style("fill", function(d) { return color(d.MethodOfLeak); })
 
.on("mouseover", function(d) {
       div.transition()
         .duration(200)
      .style("background-color", color(d.MethodOfLeak) )
         .style("opacity", .9);
    div .html(
        '<a href= "'+d.Source+'" target="_blank">' + //with a link
        d.Entity +
        "</a>" +
        "<br/>"  + numberWithCommas(d.RecordsStolen)+
        "<br/>"  + d.MethodOfLeak)     
        .style("left", (d3.event.pageX+10) + "px")             
        .style("top", (d3.event.pageY - 28) + "px");
       });
  
focus.append("g")
      .attr("class", "axis axis--x")
      .call(xAxis);

focus.append("g")
      .attr("class", "axis axis--y")
      .call(yAxis);
      
focus.append("text")
      .attr("transform", "rotate(-90)")
      .attr("y", 0 - margin.left)
      .attr("x",0 - (height / 2))
      .attr("dy", "1em")
      .style("text-anchor", "middle")
      .text("Records Stolen");  
      
svg.append("text")             
      .attr("transform",
            "translate(" + ((width + margin.right + margin.left)/2) + " ," + 30 + ")")
      .style("text-anchor", "middle")
      .text("Year");

context.append("g")
      .attr("class", "brush")
      .call(brush)
      .call(brush.move, y2.range());

// draw legend
  var legend = svg.append("g")
    .attr("class", "legend")
    .attr("transform", "translate(120,"+height/2+")");
  var legendItem = legend.selectAll(".legendItem")
      .data(color.domain())
      .enter().append("g")
      .attr("class", "legend")
      .attr("transform", function(d, i) { return "translate(220," + i * 20 + ")"; });

// draw legend colored rectangles
  legendItem.append("rect")
      .attr("x", width - 18)
      .attr("width", 18)
      .attr("height", 18)
      .style("fill", color);

// draw legendItem text
  legendItem.append("text")
      .attr("x", width - 24)
      .attr("y", 9)
      .attr("dy", ".35em")
      .style("text-anchor", "end")
      .text(function(d) { return d;})

});

//create brush function redraw scatterplot with selection
function brushed() {
  
  var selection = d3.event.selection;
  y.domain(selection.map(y2.invert, y));
  focus.selectAll(".dot")
        .attr("cx", function(d) { return x(d.Year); })
        .attr("cy", function(d) { return y(d.RecordsStolen); });
  focus.select(".axis--y").call(yAxis);
}

function type(d) {
  d.Year = parseTime(d.Year);
  d.RecordsStolen = +d.RecordsStolen;
  return d;
}

function numberWithCommas(x) {
    return x.toString().replace(/\B(?=(\d{3})+(?!\d))/g, ",");
}
</script>

https://d3js.org/d3.v4.min.js