jquery - Multiseries line chart with mouseover tooltip

Question

I've created a multi-series line chart using this bl.ocks.org code example. I've managed to recreate it on JSFiddle.

Now, I'm trying to add an x-value mouseover tooltip, which displays the a tooltip at each line when you hover its vertical position. Something like this, but for multiple lines.

I found this StackOverflow answer (it includes a JSFiddle), but I can't seem to make it work with my multiseries line chart.

svg.append("path") // this is the black vertical line to follow mouse
  .attr("class","mouseLine")  
  .style("stroke","black")
  .style("stroke-width", "1px")
  .style("opacity", "0");

var mouseCircle = causation.append("g") // for each line, add group to hold text and circle
      .attr("class","mouseCircle"); 

mouseCircle.append("circle") // add a circle to follow along path
  .attr("r", 7)
  .style("stroke", function(d) { console.log(d); return color(d.key); })
  .style("fill","none")
  .style("stroke-width", "1px"); 

mouseCircle.append("text")
  .attr("transform", "translate(10,3)"); // text to hold coordinates

var bisect = d3.bisector(function(d) { return d.YEAR; }).right; // reusable bisect to find points before/after line

svg.append('svg:rect') // append a rect to catch mouse movements on canvas
  .attr('width', width) // can't catch mouse events on a g element
  .attr('height', height)
  .attr('fill', 'none')
  .attr('pointer-events', 'all')
  .on('mouseout', function(){ // on mouse out hide line, circles and text
        d3.select(".mouseLine")
            .style("opacity", "0");
        d3.selectAll(".mouseCircle circle")
            .style("opacity", "0");
      d3.selectAll(".mouseCircle text")
            .style("opacity", "0");
  })
  .on('mouseover', function(){ // on mouse in show line, circles and text
        d3.select(".mouseLine")
            .style("opacity", "1");
         d3.selectAll(".mouseCircle circle")
            .style("opacity", "1");
        d3.selectAll(".mouseCircle text")
            .style("opacity", "1");
  })
  .on('mousemove', function() { // mouse moving over canvas
      d3.select(".mouseLine")
      .attr("d", function(){
          yRange = y.range(); // range of y axis
          var xCoor = d3.mouse(this)[0]; // mouse position in x
          var xDate = x.invert(xCoor); // date corresponding to mouse x 
          d3.selectAll('.mouseCircle') // for each circle group
              .each(function(d,i){
                 var rightIdx = bisect(data[1].values, xDate); // find date in data that right off mouse
                 var interSect = get_line_intersection(xCoor,  // get the intersection of our vertical line and the data line
                      yRange[0], 
                      xCoor, 
                      yRange[1],
                      x(data[i].values[rightIdx-1].YEAR),
                      y(data[i].values[rightIdx-1].VALUE),
                      x(data[i].values[rightIdx].YEAR),
                      y(data[i].values[rightIdx].VALUE));

              d3.select(this) // move the circle to intersection
                  .attr('transform', 'translate(' + interSect.x + ',' + interSect.y + ')');

              d3.select(this.children[1]) // write coordinates out
                  .text(xDate.toLocaleDateString() + "," + y.invert(interSect.y).toFixed(0));

              });

          return "M"+ xCoor +"," + yRange[0] + "L" + xCoor + "," + yRange[1]; // position vertical line
      });
  });

// from here: https://stackoverflow.com/a/1968345/16363
function get_line_intersection(p0_x, p0_y, p1_x, p1_y, 
    p2_x, p2_y, p3_x, p3_y)
{
    var rV = {};
    var s1_x, s1_y, s2_x, s2_y;
    s1_x = p1_x - p0_x;     s1_y = p1_y - p0_y;
    s2_x = p3_x - p2_x;     s2_y = p3_y - p2_y;

    var s, t;
    s = (-s1_y * (p0_x - p2_x) + s1_x * (p0_y - p2_y)) / (-s2_x * s1_y + s1_x * s2_y);
    t = ( s2_x * (p0_y - p2_y) - s2_y * (p0_x - p2_x)) / (-s2_x * s1_y + s1_x * s2_y);

    if (s >= 0 && s <= 1 && t >= 0 && t <= 1)
    {
        // Collision detected
        rV.x = p0_x + (t * s1_x);
        rV.y = p0_y + (t * s1_y);
    }

    return rV;
}

So, to put it simply, I want to combine my line chart JSFiddle with this tooltip JSFiddle. Does anybody know how to do this? Or is there an easier way to create a tooltip like this? Any help is appreciated!

Answer 1

The question you referenced I answered back in April. Since then, I've learned a bit more about SVG and d3, so I'll let this serve as an update to that answer.

Note, I borrowed a bit of code from @Duopixel's excellent code sample here.

Here's the commented particulars:

// append a g for all the mouse over nonsense
var mouseG = svg.append("g")
  .attr("class", "mouse-over-effects");

// this is the vertical line
mouseG.append("path")
  .attr("class", "mouse-line")
  .style("stroke", "black")
  .style("stroke-width", "1px")
  .style("opacity", "0");

// keep a reference to all our lines
var lines = document.getElementsByClassName('line');

// here's a g for each circle and text on the line
var mousePerLine = mouseG.selectAll('.mouse-per-line')
  .data(cities)
  .enter()
  .append("g")
  .attr("class", "mouse-per-line");

// the circle
mousePerLine.append("circle")
  .attr("r", 7)
  .style("stroke", function(d) {
    return color(d.name);
  })
  .style("fill", "none")
  .style("stroke-width", "1px")
  .style("opacity", "0");

// the text
mousePerLine.append("text")
  .attr("transform", "translate(10,3)");

// rect to capture mouse movements
mouseG.append('svg:rect')
  .attr('width', width)
  .attr('height', height)
  .attr('fill', 'none')
  .attr('pointer-events', 'all')
  .on('mouseout', function() { // on mouse out hide line, circles and text
    d3.select(".mouse-line")
      .style("opacity", "0");
    d3.selectAll(".mouse-per-line circle")
      .style("opacity", "0");
    d3.selectAll(".mouse-per-line text")
      .style("opacity", "0");
  })
  .on('mouseover', function() { // on mouse in show line, circles and text
    d3.select(".mouse-line")
      .style("opacity", "1");
    d3.selectAll(".mouse-per-line circle")
      .style("opacity", "1");
    d3.selectAll(".mouse-per-line text")
      .style("opacity", "1");
  })
  .on('mousemove', function() { // mouse moving over canvas
    var mouse = d3.mouse(this);

    // move the vertical line
    d3.select(".mouse-line")
      .attr("d", function() {
        var d = "M" + mouse[0] + "," + height;
        d += " " + mouse[0] + "," + 0;
        return d;
      });

    // position the circle and text
    d3.selectAll(".mouse-per-line")
      .attr("transform", function(d, i) {
        console.log(width/mouse[0])
        var xDate = x.invert(mouse[0]),
            bisect = d3.bisector(function(d) { return d.date; }).right;
            idx = bisect(d.values, xDate);

        // since we are use curve fitting we can't relay on finding the points like I had done in my last answer
        // this conducts a search using some SVG path functions
        // to find the correct position on the line
        // from http://bl.ocks.org/duopixel/3824661
        var beginning = 0,
            end = lines[i].getTotalLength(),
            target = null;

        while (true){
          target = Math.floor((beginning + end) / 2);
          pos = lines[i].getPointAtLength(target);
          if ((target === end || target === beginning) && pos.x !== mouse[0]) {
              break;
          }
          if (pos.x > mouse[0])      end = target;
          else if (pos.x < mouse[0]) beginning = target;
          else break; //position found
        }

        // update the text with y value
        d3.select(this).select('text')
          .text(y.invert(pos.y).toFixed(2));

        // return position
        return "translate(" + mouse[0] + "," + pos.y +")";
      });
  });

---

Full working code:

<!DOCTYPE html>
<html>

<head>
  <script data-require="[email protected]" data-semver="3.5.3" src="//cdnjs.cloudflare.com/ajax/libs/d3/3.5.3/d3.js"></script>
  <style>
    body {
      font: 10px sans-serif;
    }
    
    .axis path,
    .axis line {
      fill: none;
      stroke: #000;
      shape-rendering: crispEdges;
    }
    
    .x.axis path {
      display: none;
    }
    
    .line {
      fill: none;
      stroke: steelblue;
      stroke-width: 1.5px;
    }
  </style>
</head>

<body>
  <script>
    var myData = "dateNew YorkSan FranciscoAustin

2011100163.462.772.2

2011100258.059.967.7

2011100353.359.169.4

2011100455.758.868.0

2011100564.258.772.4

2011100658.857.077.0

2011100757.956.782.3

2011100861.856.878.9

2011100969.356.768.8

2011101071.260.168.7

2011101168.761.170.3

2011101261.861.575.3

2011101363.064.376.6

2011101466.967.166.6

2011101561.764.668.0

2011101661.861.670.6

2011101762.861.171.1

2011101860.859.270.0

2011101962.158.961.6

2011102065.157.257.4

2011102155.656.464.3

2011102254.460.772.4
";

    var margin = {
        top: 20,
        right: 80,
        bottom: 30,
        left: 50
      },
      width = 500 - margin.left - margin.right,
      height = 500 - margin.top - margin.bottom;

    var parseDate = d3.time.format("%Y%m%d").parse;

    var x = d3.time.scale()
      .range([0, width]);

    var y = d3.scale.linear()
      .range([height, 0]);

    var color = d3.scale.category10();

    var xAxis = d3.svg.axis()
      .scale(x)
      .orient("bottom");

    var yAxis = d3.svg.axis()
      .scale(y)
      .orient("left");

    var line = d3.svg.line()
      .interpolate("basis")
      .x(function(d) {
        return x(d.date);
      })
      .y(function(d) {
        return y(d.temperature);
      });

    var svg = d3.select("body").append("svg")
      .attr("width", width + margin.left + margin.right)
      .attr("height", height + margin.top + margin.bottom)
      .append("g")
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

    var data = d3.tsv.parse(myData);

    color.domain(d3.keys(data[0]).filter(function(key) {
      return key !== "date";
    }));

    data.forEach(function(d) {
      d.date = parseDate(d.date);
    });

    var cities = color.domain().map(function(name) {
      return {
        name: name,
        values: data.map(function(d) {
          return {
            date: d.date,
            temperature: +d[name]
          };
        })
      };
    });

    x.domain(d3.extent(data, function(d) {
      return d.date;
    }));

    y.domain([
      d3.min(cities, function(c) {
        return d3.min(c.values, function(v) {
          return v.temperature;
        });
      }),
      d3.max(cities, function(c) {
        return d3.max(c.values, function(v) {
          return v.temperature;
        });
      })
    ]);

    var legend = svg.selectAll('g')
      .data(cities)
      .enter()
      .append('g')
      .attr('class', 'legend');

    legend.append('rect')
      .attr('x', width - 20)
      .attr('y', function(d, i) {
        return i * 20;
      })
      .attr('width', 10)
      .attr('height', 10)
      .style('fill', function(d) {
        return color(d.name);
      });

    legend.append('text')
      .attr('x', width - 8)
      .attr('y', function(d, i) {
        return (i * 20) + 9;
      })
      .text(function(d) {
        return d.name;
      });

    svg.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);

    svg.append("g")
      .attr("class", "y axis")
      .call(yAxis)
      .append("text")
      .attr("transform", "rotate(-90)")
      .attr("y", 6)
      .attr("dy", ".71em")
      .style("text-anchor", "end")
      .text("Temperature (oF)");

    var city = svg.selectAll(".city")
      .data(cities)
      .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 color(d.name);
      });

    city.append("text")
      .datum(function(d) {
        return {
          name: d.name,
          value: d.values[d.values.length - 1]
        };
      })
      .attr("transform", function(d) {
        return "translate(" + x(d.value.date) + "," + y(d.value.temperature) + ")";
      })
      .attr("x", 3)
      .attr("dy", ".35em")
      .text(function(d) {
        return d.name;
      });

    var mouseG = svg.append("g")
      .attr("class", "mouse-over-effects");

    mouseG.append("path") // this is the black vertical line to follow mouse
      .attr("class", "mouse-line")
      .style("stroke", "black")
      .style("stroke-width", "1px")
      .style("opacity", "0");
      
    var lines = document.getElementsByClassName('line');

    var mousePerLine = mouseG.selectAll('.mouse-per-line')
      .data(cities)
      .enter()
      .append("g")
      .attr("class", "mouse-per-line");

    mousePerLine.append("circle")
      .attr("r", 7)
      .style("stroke", function(d) {
        return color(d.name);
      })
      .style("fill", "none")
      .style("stroke-width", "1px")
      .style("opacity", "0");

    mousePerLine.append("text")
      .attr("transform", "translate(10,3)");

    mouseG.append('svg:rect') // append a rect to catch mouse movements on canvas
      .attr('width', width) // can't catch mouse events on a g element
      .attr('height', height)
      .attr('fill', 'none')
      .attr('pointer-events', 'all')
      .on('mouseout', function() { // on mouse out hide line, circles and text
        d3.select(".mouse-line")
          .style("opacity", "0");
        d3.selectAll(".mouse-per-line circle")
          .style("opacity", "0");
        d3.selectAll(".mouse-per-line text")
          .style("opacity", "0");
      })
      .on('mouseover', function() { // on mouse in show line, circles and text
        d3.select(".mouse-line")
          .style("opacity", "1");
        d3.selectAll(".mouse-per-line circle")
          .style("opacity", "1");
        d3.selectAll(".mouse-per-line text")
          .style("opacity", "1");
      })
      .on('mousemove', function() { // mouse moving over canvas
        var mouse = d3.mouse(this);
        d3.select(".mouse-line")
          .attr("d", function() {
            var d = "M" + mouse[0] + "," + height;
            d += " " + mouse[0] + "," + 0;
            return d;
          });

        d3.selectAll(".mouse-per-line")
          .attr("transform", function(d, i) {
            console.log(width/mouse[0])
            var xDate = x.invert(mouse[0]),
                bisect = d3.bisector(function(d) { return d.date; }).right;
                idx = bisect(d.values, xDate);
            
            var beginning = 0,
                end = lines[i].getTotalLength(),
                target = null;

            while (true){
              target = Math.floor((beginning + end) / 2);
              pos = lines[i].getPointAtLength(target);
              if ((target === end || target === beginning) && pos.x !== mouse[0]) {
                  break;
              }
              if (pos.x > mouse[0])      end = target;
              else if (pos.x < mouse[0]) beginning = target;
              else break; //position found
            }
            
            d3.select(this).select('text')
              .text(y.invert(pos.y).toFixed(2));
              
            return "translate(" + mouse[0] + "," + pos.y +")";
          });
      });
      
  </script>
</body>