D3js从数组而不是文件中获取数据

时间：2014-02-07 22:57:25

标签： javascript html svg d3.js

我找到了这个优秀的d3js图表here。但是在我的情况下，我希望此图表从数组而不是tsv文件中获取值。我想让它从表[]中获取值。我怎么能这样做？因为它使用了一个函数，我不知道我应该把数组放在哪里。

Using d3-tip to add tooltips to a d3 bar chart.
<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  font: 10px sans-serif;
}

.axis path,
.axis line {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}

.bar {
  fill: orange;
}

.bar:hover {
  fill: orangered ;
}

.x.axis path {
  display: none;
}

.d3-tip {
  line-height: 1;
  font-weight: bold;
  padding: 12px;
  background: rgba(0, 0, 0, 0.8);
  color: #fff;
  border-radius: 2px;
}

/* Creates a small triangle extender for the tooltip */
.d3-tip:after {
  box-sizing: border-box;
  display: inline;
  font-size: 10px;
  width: 100%;
  line-height: 1;
  color: rgba(0, 0, 0, 0.8);
  content: "\25BC";
  position: absolute;
  text-align: center;
}

/* Style northward tooltips differently */
.d3-tip.n:after {
  margin: -1px 0 0 0;
  top: 100%;
  left: 0;
}
</style>
<body>
<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js"></script>
<script>

var margin = {top: 40, right: 20, bottom: 30, left: 40},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var formatPercent = d3.format(".0%");

var x = d3.scale.ordinal()
    .rangeRoundBands([0, width], .1);

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

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

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

var tip = d3.tip()
  .attr('class', 'd3-tip')
  .offset([-10, 0])
  .html(function(d) {
    return "<strong>Frequency:</strong> <span style='color:red'>" + d.frequency + "</span>";
  })

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 + ")");

svg.call(tip);

d3.tsv("data.tsv", type, function(error, data) {
  x.domain(data.map(function(d) { return d.letter; }));
  y.domain([0, d3.max(data, function(d) { return d.frequency; })]);

  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("Frequency");

  svg.selectAll(".bar")
      .data(data)
    .enter().append("rect")
      .attr("class", "bar")
      .attr("x", function(d) { return x(d.letter); })
      .attr("width", x.rangeBand())
      .attr("y", function(d) { return y(d.frequency); })
      .attr("height", function(d) { return height - y(d.frequency); })
      .on('mouseover', tip.show)
      .on('mouseout', tip.hide)

});

function type(d) {
  d.frequency = +d.frequency;
  return d;
}

</script>

非常感谢

2 个答案:

答案 0 :(得分：113)

D3 gallery有很多很好的示例，但很多示例都是从tab-separated values file加载数据。这是在简短示例中分离数据和可视化的一种很好的方法，但是如果您不熟悉D3和JavaScript，它可能会有点混乱，因为它需要一些关于d3.tsv（）和回调函数的基本知识来理解什么是继续。

免责声明：以下部分将提供一些非常简化的解释。

d3.tsv（）在做什么？

d3.tsv（）基本上负责从data.tsv加载数据，将其解析为名为data的变量，并将此变量发送到callback function。

d3.tsv("data.tsv", type, function(error, data) { <- This is the callback function!
  // This code is executed when the data.tsv file is loaded.
});

加载数据后，它将作为数据参数发送到函数。然后执行回调函数内的代码。因为除了作为d3.tsv（）函数的参数之外我们不需要回调函数，所以我们直接将其作为anonymous function，而不是像往常一样给它起一个名字。

这种回调和匿名函数的使用是JavaScript的典型特征，非常值得一读。 Understand JavaScript Callback Functions and Use Them和Understanding JavaScript Callbacks可以帮助您入门。

让我们看看我们如何使用这些信息来重写我们的代码。

如何重写示例以使用本地变量中的数据？

首先，我们必须创建包含数据的变量。我们将其称为“数据”，与我们的回调函数相同，并为其提供示例中的值。

var data = [
  {letter: "A", frequency: .08167},
  {letter: "B", frequency: .01492},
  {letter: "C", frequency: .02780},
  {letter: "D", frequency: .04253},
  {letter: "E", frequency: .12702},
  {letter: "F", frequency: .02288},
  {letter: "G", frequency: .02022},
  {letter: "H", frequency: .06094},
  {letter: "I", frequency: .06973},
  {letter: "J", frequency: .00153},
  {letter: "K", frequency: .00747},
  {letter: "L", frequency: .04025},
  {letter: "M", frequency: .02517},
  {letter: "N", frequency: .06749},
  {letter: "O", frequency: .07507},
  {letter: "P", frequency: .01929},
  {letter: "Q", frequency: .00098},
  {letter: "R", frequency: .05987},
  {letter: "S", frequency: .06333},
  {letter: "T", frequency: .09056},
  {letter: "U", frequency: .02758},
  {letter: "V", frequency: .01037},
  {letter: "W", frequency: .02465},
  {letter: "X", frequency: .00150},
  {letter: "Y", frequency: .01971},
  {letter: "Z", frequency: .00074}
];

在调用d3.tsv之前将此变量放在某处，因为回调函数中的代码依赖于此变量。

我选择将数据表示为具有字母和频率属性的对象列表。这是一种简单的方法，因为它非常类似于d3.tsv（）解析.tsv文件的方式。这意味着我们不必更改回调函数中的代码，因为它已经预期变量具有此格式的数据。如果您愿意，可以更改此项，但请记住更改回调代码使用“数据”变量的方式。

现在我们可以删除与d3.tsv调用相关的代码，只留下回调函数中包含的代码。所以这段代码：

d3.tsv("data.tsv", type, function(error, data) {
  x.domain(data.map(function(d) { return d.letter; }));
  // code omitted.
  .on('mouseout', tip.hide)
});

成为这段代码：

x.domain(data.map(function(d) { return d.letter; }));
// code omitted.
.on('mouseout', tip.hide)

现在示例应该正常工作。您可以使用此策略来重写D3库中的其他示例。

最后，我已经包含了新index.html文件的代码。可以在JSFiddle找到一个工作示例。

<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  font: 10px sans-serif;
}

.axis path,
.axis line {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}

.bar {
  fill: orange;
}

.bar:hover {
  fill: orangered ;
}

.x.axis path {
  display: none;
}

.d3-tip {
  line-height: 1;
  font-weight: bold;
  padding: 12px;
  background: rgba(0, 0, 0, 0.8);
  color: #fff;
  border-radius: 2px;
}

/* Creates a small triangle extender for the tooltip */
.d3-tip:after {
  box-sizing: border-box;
  display: inline;
  font-size: 10px;
  width: 100%;
  line-height: 1;
  color: rgba(0, 0, 0, 0.8);
  content: "\25BC";
  position: absolute;
  text-align: center;
}

/* Style northward tooltips differently */
.d3-tip.n:after {
  margin: -1px 0 0 0;
  top: 100%;
  left: 0;
}
</style>
<body>
<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://labratrevenge.com/d3-tip/javascripts/d3.tip.v0.6.3.js"></script>
<script>

var margin = {top: 40, right: 20, bottom: 30, left: 40},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var formatPercent = d3.format(".0%");

var x = d3.scale.ordinal()
    .rangeRoundBands([0, width], .1);

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

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

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

var tip = d3.tip()
  .attr('class', 'd3-tip')
  .offset([-10, 0])
  .html(function(d) {
    return "<strong>Frequency:</strong> <span style='color:red'>" + d.frequency + "</span>";
  })

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 + ")");

svg.call(tip);

// The new data variable.
var data = [
  {letter: "A", frequency: .08167},
  {letter: "B", frequency: .01492},
  {letter: "C", frequency: .02780},
  {letter: "D", frequency: .04253},
  {letter: "E", frequency: .12702},
  {letter: "F", frequency: .02288},
  {letter: "G", frequency: .02022},
  {letter: "H", frequency: .06094},
  {letter: "I", frequency: .06973},
  {letter: "J", frequency: .00153},
  {letter: "K", frequency: .00747},
  {letter: "L", frequency: .04025},
  {letter: "M", frequency: .02517},
  {letter: "N", frequency: .06749},
  {letter: "O", frequency: .07507},
  {letter: "P", frequency: .01929},
  {letter: "Q", frequency: .00098},
  {letter: "R", frequency: .05987},
  {letter: "S", frequency: .06333},
  {letter: "T", frequency: .09056},
  {letter: "U", frequency: .02758},
  {letter: "V", frequency: .01037},
  {letter: "W", frequency: .02465},
  {letter: "X", frequency: .00150},
  {letter: "Y", frequency: .01971},
  {letter: "Z", frequency: .00074}
];

// The following code was contained in the callback function.
x.domain(data.map(function(d) { return d.letter; }));
y.domain([0, d3.max(data, function(d) { return d.frequency; })]);

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("Frequency");

svg.selectAll(".bar")
    .data(data)
  .enter().append("rect")
    .attr("class", "bar")
    .attr("x", function(d) { return x(d.letter); })
    .attr("width", x.rangeBand())
    .attr("y", function(d) { return y(d.frequency); })
    .attr("height", function(d) { return height - y(d.frequency); })
    .on('mouseover', tip.show)
    .on('mouseout', tip.hide)

function type(d) {
  d.frequency = +d.frequency;
  return d;
}

</script>

答案 1 :(得分：0)

整个d3.tsv()（或d3.json()或其他内容）是可选的。因此，只需使用其回调剥离它，然后直接使用您的数据即可：

var fruits = ['apple', 'mango', 'banana', 'orange'];
d3.select('ul')
    .selectAll('li')
    .data(fruits)
    .enter()
    .append('li')
    .text(function(d) { return d; });

PS：这就是为什么您找不到d3.data()函数之类的原因，我搜索了一段时间；-）

相关问题
最新问题