问在折线图顶部显示值

EN

lineSvg.selectAll("path")
  .data(data)
  .enter().append("text")
  .attr("class", "line")
  .attr("text-anchor", "middle")
  .attr("x", function(d) { return 10; })
  .attr("y", function(d) { return yscale(d.value) - 5; })
  .text(function(d) { return d.value; });

var data = [{
    "date": "2018-1",
    "value": 40.13,
    "status": 1
}, {
    "date": "2018-2",
    "value": 45.88,
    "status": 1
}, {
    "date": "2018-3",
    "value": 50.89,
    "status": 1
}, {
    "date": "2018-4",
    "value": 55.87,
    "status": 1
}, {
    "date": "2018-5",
    "value": 88.54,
    "status": 1
}, {
    "date": "2018-6",
    "value": 74.41,
    "status": 1
}, {
    "date": "2018-7",
    "value": 98.56,
    "status": 1
}, {
    "date": "2018-8",
    "value": 81.05,
    "status": 1
}, {
    "date": "2018-9",
    "value": 58.13,
    "status": 1
}, {
    "date": "2018-10",
    "value": 95.86,
    "status": 1
}, {
    "date": "2018-11",
    "value": 78.13,
    "status": 1
}, {
    "date": "2018-12",
    "value": 98.86,
    "status": 1
}, {
    "date": "2019-1",
    "value": 105.86,
    "status": 0
}, {
    "date": "2019-2",
    "value": 110.86,
    "status": 0
}];

/* Monday 2012 */
var data1 = data
var dateformat = "%Y-%m"
drawTimeSeriesGraph(data1, dateformat);

/* 
  Tooltip from: http://bl.ocks.org/d3noob/6eb506b129f585ce5c8a
  line graph from here: http://www.d3noob.org/2012/12/starting-with-basic-d3-line-graph.html
*/

function drawTimeSeriesGraph(data, dateformat) {

    //Set bounds for red dots
    var lbound = 0.045,
        ubound = 0.075;

    // Set the dimensions of the canvas / graph
    var margin = {
        top: 50,
        right: 150,
        bottom: 50,
        left: 50
    },
        width = 900 - margin.left - margin.right,
        height = 270 - margin.top - margin.bottom;

    // Parse the date / time
    var parseDate = d3.time.format(dateformat).parse,
        formatDate = d3.time.format(dateformat),
        bisectDate = d3.bisector(function(d) {
            return d.date;
        }).left;

    // Set the ranges
    var x = d3.time.scale().range([0, width]);
    var y = d3.scale.linear().range([height, 0]);

    // Define the axes
    var xAxis = d3.svg.axis().scale(x)
      .orient("bottom").ticks(10);

    var yAxis = d3.svg.axis().scale(y)
      .orient("left").ticks(10);

    // Define the line
    var valueline = d3.svg.line()
      .x(function(d) {
          return x(d.date);
      })
      .y(function(d) {
          return y(d.value);
      }).interpolate("linear");
    var full_date = new Date();
    var day = full_date.getDay(); //returns 0 - 6
    var month = full_date.getMonth() + 1; //returns 0 - 11
    var year = full_date.getFullYear(); //returns 4 digit year ex: 2000
    var my = year + "-" + month;
    //alert(my);
    // Adds the svg canvas
    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 lineSvg = svg.append("g");

    var focus = svg.append("g")
      .style("display", "none");

    // Get the data
    data.forEach(function(d) {
        d.date = parseDate(d.date);
        d.value = +d.value;
    });

    // Scale the range of the data
    x.domain(d3.extent(data, function(d) {
        return d.date;
    }));
    y.domain([0, d3.max(data, function(d) {
        return d.value;
    })]);
    //Use below if instead you want to define the y limits:
    //y.domain([0, 0.11]);

    // Add the valueline path.
    var lineGraph2 = lineSvg.append("path")
      .attr("class", "line")
      .attr("d", valueline(data.filter(function(d) {
          return d.status > 0;
      })))
      .attr("stroke", "blue")
      .attr("stroke-width", 2)
      .attr("fill", "none");

    var lineGraph1 = lineSvg.append("path")
      .attr("class", "line")
      .attr("d", valueline(data.slice(-3)))
      .attr("stroke", "red")
      .attr("stroke-width", 2)
      .attr("fill", "none");


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

    // Add the Y Axis
    svg.append("g")
      .attr("class", "y axis")
      .call(yAxis);

    // append the x line
    focus.append("line")
      .attr("class", "x")
      .style("stroke", "blue")
      .style("stroke-dasharray", "3,3")
      .style("opacity", 0.5)
      .attr("y1", 0)
      .attr("y2", height);

    // append the y line
    focus.append("line")
      .attr("class", "y")
      .style("stroke", "blue")
      .style("stroke-dasharray", "3,3")
      .style("opacity", 0.5)
      .attr("x1", width)
      .attr("x2", width);

    // append the circle at the intersection
    focus.append("circle")
      .attr("class", "y")
      .style("fill", "none")
      .style("stroke", "blue")
      .attr("r", 4);

    // place the value at the intersection
    focus.append("text")
      .attr("class", "y1")
      .style("stroke", "white")
      .style("stroke-width", "3.5px")
      .style("opacity", 0.8)
      .attr("dx", 8)
      .attr("dy", "-.3em");

    focus.append("text")
      .attr("class", "y2")
      .attr("dx", 8)
      .attr("dy", "-.3em");

    // place the date at the intersection
    focus.append("text")
      .attr("class", "y3")
      .style("stroke", "white")
      .style("stroke-width", "3.5px")
      .style("opacity", 0.8)
      .attr("dx", 8)
      .attr("dy", "1em");

    focus.append("text")
      .attr("class", "y4")
      .attr("dx", 8)
      .attr("dy", "1em");

    // append the rectangle to capture mouse
    svg.append("rect")
      .attr("width", width)
      .attr("height", height)
      .style("fill", "none")
      .style("pointer-events", "all")
      .on("mouseover", function() {
          focus.style("display", null);
      })
      .on("mouseout", function() {
          focus.style("display", "none");
      })
      .on("mousemove", mousemove);

    function mousemove() {
        var x0 = x.invert(d3.mouse(this)[0]),
          i = bisectDate(data, x0, 1),
          d0 = data[i - 1],
          d1 = data[i],
          d = x0 - d0.date > d1.date - x0 ? d1 : d0;

        focus.select("circle.y")
          .attr("transform", "translate(" + x(d.date) + "," + y(d.value) + ")");

        focus.select("text.y1")
          .attr("transform", "translate(" + x(d.date) + "," + y(d.value) + ")")
          .text(d.value.toFixed(2));

        focus.select("text.y2")
          .attr("transform", "translate(" + x(d.date) + "," + y(d.value) + ")")
          .text(d.value.toFixed(2));

        focus.select("text.y3")
          .attr("transform", "translate(" + x(d.date) + "," + y(d.value) + ")")
          .text(formatDate(d.date));

        focus.select("text.y4")
          .attr("transform", "translate(" + x(d.date) + "," + y(d.value) + ")")
          .text(formatDate(d.date));

        focus.select(".x")
          .attr("transform", "translate(" + x(d.date) + "," + y(d.value) + ")")
          .attr("y2", height - y(d.value));

        focus.select(".y")
          .attr("transform", "translate(" + width * -1 + "," + y(d.value) + ")")
          .attr("x2", width + width);
    };

    svg.append("text")
      .attr("x", (width / 2))
      .attr("y", 0 - (margin.top / 2))
      .attr("text-anchor", "middle")
      .style("font-size", "16px")
      .style("text-decoration", "underline")
};