var pie = d3.pie() .value(d => d.value); var arc = d3.arc() .innerRadius(radius * 0.5) .outerRadius(radius * 0.8); var arcLabel = d3.arc() .innerRadius(radius * 0.9) .outerRadius(radius * 0.9); var arcs = pie(data); 解释一下这段代码
时间: 2023-06-06 10:04:48 浏览: 50
这段代码使用了D3.js库,用来绘制饼图。首先定义了一个饼图对象,通过传入一个数据集d来计算饼图各个扇形的角度大小。然后定义了两个弧形对象,一个是内边界半径为半径的一半,外边界半径为半径的0.8倍,用来绘制饼图的扇形部分;另一个是内外边界半径相等,用来绘制扇形区域内部的文本标签。最后使用饼图对象对数据集进行计算,并存储在arcs变量中,用于绘制饼图。
相关问题
D3.js实现3D饼图
作为一名AI助手,我无法展示图形,但我可以提供D3.js实现3D饼图的代码,供您参考:
```html
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>D3 3D Pie Chart</title>
<script src="https://d3js.org/d3.v5.min.js"></script>
</head>
<body>
<script>
var width = 500;
var height = 500;
var radius = Math.min(width, height) / 2;
var depth = 30;
var color = d3.scaleOrdinal(d3.schemeCategory10);
var data = [
{label: "A", value: 20},
{label: "B", value: 30},
{label: "C", value: 50}
];
var svg = d3.select("body")
.append("svg")
.attr("width", width)
.attr("height", height);
var pie = d3.pie()
.sort(null)
.value(function(d) { return d.value; });
var arc = d3.arc()
.outerRadius(radius - 10)
.innerRadius(0);
var arc3d = d3.arc()
.outerRadius(radius - 10)
.innerRadius(0)
.startAngle(function(d) { return d.startAngle; })
.endAngle(function(d) { return d.endAngle; });
var pieData = pie(data);
var g = svg.append("g")
.attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");
var path = g.selectAll("path")
.data(pieData)
.enter().append("path")
.attr("fill", function(d, i) { return color(i); })
.attr("d", arc);
path.on("mouseover", function(d) {
var path3d = d3.select(this)
.transition()
.duration(200)
.attr("d", arc3d);
path3d.append("svg:title").text(d.data.label + " - " + d.data.value + "%");
});
path.on("mouseout", function(d) {
d3.select(this)
.transition()
.duration(200)
.attr("d", arc);
});
var paths = d3.selectAll("path");
var zScale = d3.scaleLinear()
.domain([0, paths.size()])
.range([0, depth]);
paths.each(function(d, i) {
var path = d3.select(this);
var prev = path.attr("d");
var next = prev.replace("A", "L");
var pos1 = prev.indexOf("A");
var pos2 = prev.indexOf(" ", pos1) + 1;
var pos3 = prev.indexOf(",", pos2) + 1;
var pos4 = prev.indexOf(" ", pos3) + 1;
var pos5 = prev.indexOf(",", pos4) + 1;
var slice = prev.substring(pos1, pos2);
var rx = prev.substring(pos2, pos3 - 1);
var ry = prev.substring(pos3, pos4 - 1);
var largeArc = prev.substring(pos4, pos5 - 1);
var sweep = prev.substring(pos5, prev.indexOf(" ", pos5));
var endAngle = d.endAngle;
var startAngle = d.startAngle;
var midAngle = startAngle + (endAngle - startAngle) / 2;
var x1 = Math.cos(midAngle) * (radius - 10);
var y1 = Math.sin(midAngle) * (radius - 10);
var x2 = Math.cos(midAngle) * (radius - 10 + zScale(i));
var y2 = Math.sin(midAngle) * (radius - 10 + zScale(i));
next += "L" + x1 + "," + y1 + " ";
next += "L" + x2 + "," + y2 + " ";
var center = arc.centroid(d);
center[2] = zScale(i);
next += "A" + rx + "," + ry + " " + largeArc + " " + sweep + " " + center[0] + "," + center[1];
path.attr("d", next);
});
</script>
</body>
</html>
```
这个代码会生成一个3D饼图,其中包含三个部分,分别对应数据中的A、B、C。当鼠标移动到图形上时,会显示当前部分的标签和占比。
flutter app中用D3.js画一个饼图
要在Flutter应用程序中使用D3.js绘制饼图,你可以使用flutter_webview_plugin插件将D3.js代码嵌入到WebView中。
以下是实现步骤:
1. 添加flutter_webview_plugin插件到你的Flutter项目中。
```yaml
dependencies:
flutter_webview_plugin: ^0.3.10
```
2. 创建一个WebView并加载D3.js代码。
```dart
import 'package:flutter_webview_plugin/flutter_webview_plugin.dart';
import 'package:flutter/material.dart';
class PieChart extends StatelessWidget {
@override
Widget build(BuildContext context) {
return WebviewScaffold(
url: new Uri.dataFromString('''
<html>
<head>
<script src="https://d3js.org/d3.v4.min.js"></script>
</head>
<body>
<div id="chart"></div>
<script>
var data = [10, 20, 30, 40, 50];
var width = 400;
var height = 400;
var radius = Math.min(width, height) / 2;
var color = d3.scaleOrdinal()
.range(["#98abc5", "#8a89a6", "#7b6888", "#6b486b", "#a05d56"]);
var svg = d3.select("#chart")
.append("svg")
.attr("width", width)
.attr("height", height)
.append("g")
.attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");
var arc = d3.arc()
.outerRadius(radius - 10)
.innerRadius(0);
var pie = d3.pie()
.sort(null)
.value(function(d) { return d; });
var g = svg.selectAll(".arc")
.data(pie(data))
.enter().append("g")
.attr("class", "arc");
g.append("path")
.attr("d", arc)
.style("fill", function(d) { return color(d.data); });
</script>
</body>
</html>
''', mimeType: 'text/html').toString(),
withZoom: false,
withLocalStorage: true,
);
}
}
```
这里我们使用了D3.js的示例代码来绘制一个简单的饼图。你可以替换它为你自己的代码。
3. 在你的应用程序中使用PieChart小部件。
```dart
void main() => runApp(MaterialApp(home: PieChart()));
```
这样,你就可以在Flutter应用程序中使用D3.js绘制饼图了。