Javascript 将转换折线图转换为D3 v4

我在v4上构建示例的变体已经有一段时间了。我有它的工作没有错误，但我不能得到面积块渲染正确

我相信我可能没有正确引用数据。也许我的语法对区域或d[城市]的调用不正确？我知道在第四版中已经改变了

我还将数据读入一个名为area而不是line的变量，因为我希望它是一个面积图

以下是基本代码：

var margin = {top: 20, right: 80, bottom: 30, left: 50},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var city = "New York",
    parseDate = d3.timeParse('%Y%m%d');

var xScale = d3.scaleTime()
    .range([0, width]);

var yScale = d3.scaleLinear()
    .range([height, 0]);

var xAxis = d3.axisBottom(xScale);

var yAxis = d3.axisLeft(yScale);

var area = d3.area()
    .x(d => xScale(d.date))
    .y0(yScale(yScale.domain()[0]))
    .y1(d => yScale(d.city))
    .curve(d3.curveCatmullRom.alpha(0.5));

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 + ")");

d3.tsv("data2.tsv", function(error, data) {
  if (error) throw error;

  data.forEach(function(d) {
    d.date = parseDate(d.date);
    d["New York"] = +d["New York"];
    d["San Francisco"] = +d["San Francisco"];
  });

  xScale.domain([data[0].date, data[data.length - 1].date]);
  yScale.domain(d3.extent(data, function(d) { return d[city]; }));

  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)");

  /*svg.append("path")
      .datum(data)
      .attr("class", "area")
      .attr("d", area);*/

svg
    .selectAll('.area')
    .data(data)
    .enter()
    .append('path')
    .attr('class', 'area')
    .attr('d', area);
    /*.style('stroke', (d, i) => ['#FF9900', '#3369E8'][i])
    .style('stroke-width', 2)
    .style('fill', (d, i) => ['#FF9900', '#3369E8'][i])
    .style('fill-opacity', 0.5);*/

  svg.append("text")
      .datum(data[data.length - 1])
      .attr("class", "label")
      .attr("transform", transform)
      .attr("x", 3)
      .attr("dy", ".35em")
      .text(city);

  d3.selectAll("input").on("change", change);

  /*var timeout = setTimeout(function() {
    d3.select("input[value=\"San Francisco\"]").property("checked", true).each(change);
  }, 2000);*/

  function change() {
    //clearTimeout(timeout);

    city = this.value;

    // First transition the line & label to the new city.
    var t0 = svg.transition().duration(750);
    t0.selectAll(".area").attr("d", area);
    t0.selectAll(".label").attr("transform", transform).text(city);

    /*Then transition the y-axis.
    y.domain(d3.extent(data, function(d) { return d[city]; }));
    var t1 = t0.transition();
    t1.selectAll(".line").attr("d", line);
    t1.selectAll(".label").attr("transform", transform);
    t1.selectAll(".y.axis").call(yAxis);*/
  }

  function transform(d) {
    return "translate(" + xScale(d.date) + "," + yScale(d[city]) + ")";
  }
});

（尽管我不确定tsv文件是否被正确读取）

---

希望有人能发现这个问题，因为它对我来说编译得很好，但没有显示任何内容。

代码中的主要问题：

var area = d3.area()
    .x(d => xScale(d.date))
    .y0(yScale(yScale.domain()[0]))//incorrect as the extent is not defined
    .y1(d => yScale(d.city))
    .curve(d3.curveCatmullRom.alpha(0.5));

取而代之的是：

var area = d3.area()
    .x(d => xScale(d.date))
    .y1((d) => yScale(d[city]))
    .curve(d3.curveCatmullRom.alpha(0.5))

另一个问题

svg
    .selectAll('.area')
    .data(data) <--- it should be datum since you making a single path
    .enter()
    .append('path')
    .attr('class', 'area')
    .attr('d', area);

稍后，当您将数据块集设置为y0时

yScale.domain(d3.extent(data, function(d) { return d[city]; }));
area.y0(yScale(yScale.domain()[0]));

过渡中的其他琐碎修复

---

工作代码

请欣赏正确的结果和您花时间解释的更改。这很好用。

yScale.domain(d3.extent(data, function(d) { return d[city]; }));
area.y0(yScale(yScale.domain()[0]));