multi-line plot

forked from eric-bunch's block: multi-line plot

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <style>
.line {
  fill: none;
}
    .overlay {
  fill: none;
  pointer-events: all;
}

.focus circle {
  fill: none;
  stroke: steelblue;
}
</style>
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <style>
    body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
  </style>
</head>

<body>
  <svg class="d3-viz" width="960" height="500"></svg>
  
  <script>
    var svg = d3.select('.d3-viz'),
margin = {top: 20, right: 80, bottom: 30, left: 50},
width = svg.attr("width") - margin.left - margin.right,
height = svg.attr("height") - margin.top - margin.bottom,
g = svg.append("g").attr("transform", "translate(" + margin.left + "," + margin.top + ")");
    
var bisect = d3.bisector(function(d) { return d.x; }).left;

var x = d3.scaleLinear().range([0, width]),
    y = d3.scaleLinear().range([height, 0]),
    z = d3.scaleOrdinal(d3.schemeCategory10);

var line = d3.line()
.x(function(d) {
  return x(d.x);
})
.y(function(d) {
  return y(d.y);
});

d3.json('temperature2.json', function(error, data){
  if (error) throw error;

x.domain(d3.extent(data['0'].values, function(c){return c.x}));
  y.domain([
    d3.min(data, function(c) { return d3.min(c.values, function(d) { return d.y; }); }),
    d3.max(data, function(c) { return d3.max(c.values, function(d) { return d.y; }); })
  ]);
  
  z.domain(data, function(c) { return c.id; });

g.append("g")
      .attr("class", "axis axis--x")
      .attr("transform", "translate(0," + height + ")")
      .call(d3.axisBottom(x));

g.append("g")
      .attr("class", "axis axis--y")
      .call(d3.axisLeft(y))
    .append("text")
      .attr("transform", "rotate(-90)")
      .attr("y", 6)
      .attr("dy", "0.71em")
      .attr("fill", "#000")
      .text("Temperature, ºF");

var city = g.selectAll(".city")
    .data(data)
    .enter().append("g")
      .attr("class", "city");

city.append("path")
      .attr("class", "line")
      .attr("d", function(d) { return line(d.values); })
      .style("stroke", function(d) { return z(d.id); });

city.append("text")
      .datum(function(d) { return {id: d.id, value: d.values[d.values.length - 1]}; })
      .attr("transform", function(d) { return "translate(" + x(d.value.x) + "," + y(d.value.y) + ")"; })
      .attr("x", 3)
      .attr("dy", "0.35em")
      .style("font", "10px sans-serif")
      .text(function(d) { return d.id; });
  
  
  var focus = svg.append("g")
          .attr("class", "focus")
          .style("display", "none");

focus.append("circle")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
          .attr("r", 3.5);

focus.append("text")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
          .attr("x", 9)
          .attr("dy", ".35em");

svg.append("rect")
          .attr("class", "overlay")
          .attr("width", width)
          .attr("height", height)
      		.attr("transform", "translate(" + margin.left + "," + margin.top + ")")
          .on("mouseover", function() { focus.style("display", null); })
          .on("mouseout", function() { focus.style("display", "none"); })
          .on("mousemove", mousemove);

function mousemove() {
        var coordinates = d3.mouse(this),
        		x0 = x.invert(coordinates[0]),
            y0 = y.invert(coordinates[1]),
            i = bisect(data[0].values, x0),
            d0 = data[0].values[i - 1],
            d1 = data[0].values[i],
            d = x0 - d0.x > d1.x - x0 ? d1 : d0;
//             console.log(x0,y0,i);
//         		console.log(coordinates);
        focus.attr("transform", "translate(" + x(d.x) + "," + y(data[0].values[i].y) + ")");
        focus.select("text").text(data[0].values[i].y);
      }

});

</script>
</body>

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