javascript – D3js从数组而不是文件中获取数据
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内容图文
我发现这个优秀的d3js图表here.但在我的情况下,我希望这个图表从数组而不是tsv文件中取值.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,我不知道我应该把我的数组放在哪里.
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
解决方法:
D3 gallery有很多很好的例子,但很多例子都是从tab-separated values file加载它们的数据.这是一个很好的方法,可以在短的例子中分离数据和可视化,但是如果你是D3的新手,可能会有点混乱. JavaScript,因为它需要一些关于d3.tsv()和回调函数的基本知识才能理解正在发生的事情.
免责声明：以下部分将给出一些非常简化的解释.
什么是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.由于除了作为d3.tsv()函数的参数之外我们不需要回调函数,我们直接将其作为anonymous function,而不是像往常一样给它一个名称.
这种回调和匿名函数的使用是JavaScript的典型特征,值得一读. Understand JavaScript Callback Functions and Use Them和Understanding JavaScript Callbacks应该让你入门.
让我们看看我们如何使用这些信息来重写代码.
如何重写示例以使用局部变量中的数据？
首先,我们必须创建包含数据的变量.我们称之为“数据”,与我们的回调函数相同,并给出示例中的值.
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)
});
成为这个代码：
x.domain(data.map(function(d) { return d.letter; }));
// code omitted.
.on('mouseout', tip.hide)
现在这个例子应该运行正常.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.一个工作实例可以在JSFiddle找到.
<!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>
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