如何启动和停止D3气泡图的动画

Question

我正在努力复制健康与健康财富国家图表。

http://bost.ocks.org/mike/nations/：

当我点击开始时，图表的动画效果很好，如果我点击停止动画停止。但是，如果我下次点击开始，它从头开始而不是从我停止的地方开始？我如何从我离开的地方制作动画？

以下是代码：

<h1>The Wealth & Health of Nations</h1>

<p id="chart"></p>
<input type="submit" value="Start" onclick=start();>
<input type="submit" value="Stop" onclick=stop();>

<script src="http://d3js.org/d3.v2.js?2.8.1"></script>
<script>

// Various accessors that specify the four dimensions of data to visualize.
function x(d) { return d.income; }
function y(d) { return d.lifeExpectancy; }
function radius(d) { return d.population; }
function color(d) { return d.region; }
function key(d) { return d.name; }

// Chart dimensions.
var margin = {top: 29.5, right: 29.5, bottom: 29.5, left: 59.5},
    width = 960 - margin.right,
    height = 500 - margin.top - margin.bottom;

// Various scales. These domains make assumptions of data, naturally.
var xScale = d3.scale.log().domain([300, 1e5]).range([0, width]),
    yScale = d3.scale.linear().domain([10, 85]).range([height, 0]),
    radiusScale = d3.scale.sqrt().domain([0, 5e8]).range([0, 40]),
    colorScale = d3.scale.category10();

// The x & y axes.
var xAxis = d3.svg.axis().orient("bottom").scale(xScale).ticks(12, d3.format(",d")),
    yAxis = d3.svg.axis().scale(yScale).orient("left");

// Create the SVG container and set the origin.
var svg = d3.select("#chart").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 + ")");

// 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);

// Add an x-axis label.
svg.append("text")
    .attr("class", "x label")
    .attr("text-anchor", "end")
    .attr("x", width)
    .attr("y", height - 6)
    .text("income per capita, inflation-adjusted (dollars)");

// Add a y-axis label.
svg.append("text")
    .attr("class", "y label")
    .attr("text-anchor", "end")
    .attr("y", 6)
    .attr("dy", ".75em")
    .attr("transform", "rotate(-90)")
    .text("life expectancy (years)");

// Add the year label; the value is set on transition.
var label = svg.append("text")
    .attr("class", "year label")
    .attr("text-anchor", "end")
    .attr("y", height - 24)
    .attr("x", width)
    .text(2000);



function start()
{
//alert("Start Clicked");
// Load the data.
d3.json("nations_new.json", function(nations) {

  // A bisector since many nation's data is sparsely-defined.
  var bisect = d3.bisector(function(d) { return d[0]; });

  // Add a dot per nation. Initialize the data at 2000, and set the colors.
  var dot = svg.append("g")
      .attr("class", "dots")
    .selectAll(".dot")
      .data(interpolateData(2000))
    .enter().append("circle")
      .attr("class", "dot")
      .style("fill", function(d) { return colorScale(color(d)); })
      .call(position)
      .sort(order);

  // Add a title.
  dot.append("title")
      .text(function(d) { return d.name; });

  // Add an overlay for the year label.
  var box = label.node().getBBox();

  var overlay = svg.append("rect")
        .attr("class", "overlay")
        .attr("x", box.x)
        .attr("y", box.y)
        .attr("width", box.width)
        .attr("height", box.height);
        //.on("mouseover", enableInteraction);

  // Start a transition that interpolates the data based on year.
  svg.transition()
      .duration(30000)
      .ease("linear")
      .tween("year", tweenYear)
      .each("end", enableInteraction);

  // Positions the dots based on data.
  function position(dot) {
    dot .attr("cx", function(d) { return xScale(x(d)); })
        .attr("cy", function(d) { return yScale(y(d)); })
        .attr("r", function(d) { return radiusScale(radius(d)); });
  }

  // Defines a sort order so that the smallest dots are drawn on top.
  function order(a, b) {
    return radius(b) - radius(a);
  }

  // After the transition finishes, you can mouseover to change the year.
  function enableInteraction() {
    var yearScale = d3.scale.linear()
        .domain([2000, 2009])
        .range([box.x + 10, box.x + box.width - 10])
        .clamp(true);

    // Cancel the current transition, if any.
    svg.transition().duration(0);

    overlay
        .on("mouseover", mouseover)
        .on("mouseout", mouseout)
        .on("mousemove", mousemove)
        .on("touchmove", mousemove);

    function mouseover() {
      label.classed("active", true);
    }

    function mouseout() {
      label.classed("active", false);
    }

    function mousemove() {
      displayYear(yearScale.invert(d3.mouse(this)[0]));
    }
  }

  // Tweens the entire chart by first tweening the year, and then the data.
  // For the interpolated data, the dots and label are redrawn.
  function tweenYear() {
    var year = d3.interpolateNumber(2000, 2009);
    return function(t) { displayYear(year(t)); };
  }

  // Updates the display to show the specified year.
  function displayYear(year) {
    dot.data(interpolateData(year), key).call(position).sort(order);
    label.text(Math.round(year));
  }

  // Interpolates the dataset for the given (fractional) year.
  function interpolateData(year) {
    return nations.map(function(d) {
      return {
        name: d.name,
        region: d.region,
        income: interpolateValues(d.income, year),
        population: interpolateValues(d.population, year),
        lifeExpectancy: interpolateValues(d.lifeExpectancy, year)
      };
    });
  }

  // Finds (and possibly interpolates) the value for the specified year.
  function interpolateValues(values, year) {
    var i = bisect.left(values, year, 0, values.length - 1),
        a = values[i];
    if (i > 0) {
      var b = values[i - 1],
          t = (year - a[0]) / (b[0] - a[0]);
      return a[1] * (1 - t) + b[1] * t;
    }
    return a[1];
  }
});

}


function stop()
{
//alert("stop Clicked");
svg.transition().duration(0);

}

json文件是：

[
{

    "name":"Angola",
    "region":"Sub-Saharan Africa",
    "income":[[2000,2446.65],[2001,2479.69],[2002,2773.29],[2003,2785.39],[2004,3007.11],[2005,3533],[2006,4069.56],[2007,4755.46],[2008,5228.74],[2009,5055.59]],
    "population":[[2000,10442812],[2001,10623424],[2002,10866106],[2003,11186202],[2004,11521432],[2005,11827315],[2006,12127071],[2007,12420476],[2008,12707546]],
    "lifeExpectancy":[[2000,43.56],[2001,43.86],[2002,44.22],[2003,44.61],[2004,45.05],[2005,45.52],[2006,46.02],[2007,46.54],[2008,47.06],[2009,47.58]]
},

{

    "name":"china",
    "region":"East Asia & Pacific",
    "income":[[2000,12446.65],[2001,12479.69],[2002,12773.29],[2003,12785.39],[2004,12007.11],[2005,12533],[2006,12069.56],[2007,12755.46],[2008,12228.74],[2009,12055.59]],
    "population":[[2000,31542812],[2001,31623424],[2002,31866106],[2003,32186202],[2004,31521432],[2005,31827315],[2006,32127071],[2007,32420476],[2008,32707546]],
    "lifeExpectancy":[[2000,53.56],[2001,63.86],[2002,64.22],[2003,64.61],[2004,76.05],[2005,66.52],[2006,86.02],[2007,87.54],[2008,89.06],[2009,68.58]]
},


{

    "name":"India",
    "region":"South Asia",
    "income":[[2000,22446.65],[2001,22479.69],[2002,22773.29],[2003,22785.39],[2004,22007.11],[2005,22533],[2006,22069.56],[2007,22755.46],[2008,22228.74],[2009,22055.59]],
    "population":[[2000,41542812],[2001,41623424],[2002,41866106],[2003,42186202],[2004,41521432],[2005,41827315],[2006,42127071],[2007,42420476],[2008,42707546],[2009,42707546]],
    "lifeExpectancy":[[2000,43.56],[2001,43.86],[2002,44.22],[2003,64.61],[2004,56.05],[2005,56.52],[2006,66.02],[2007,68.54],[2008,67.06],[2009,73.58]]
}


]

Answer 1

在start功能中，您需要跟踪当前显示的年份，例如使用全局变量：

var thisYear = 2000;

// lots of code...

function displayYear(year) {
  thisYear = year;
  dot.data(interpolateData(year), key).call(position).sort(order);
  label.text(Math.round(year));
}

然后，您需要根据该变量的值修改它开始的年份：

function tweenYear() {
  var year = d3.interpolateNumber(thisYear, 2009);
  return function(t) { displayYear(year(t)); };
}

Answer 2

我正在做一些非常相似的事情，Lars的建议让我走得很远。但是，每次开始时我都会不断重复点。我后来发现了以下内容：

如果您想要在每次选择开始按钮时都不重复点，则需要将以下代码添加为start()函数的一部分，理想情况是在点之前最初添加：

svg.selectAll(".dot").remove()

这将删除以前的.dot元素;假设您已经设置了Lars提到的thisYear全局变量，随后会创建新的.dot元素。