小编之前已经跟大家分享过了《D3.js实现柱状图的方法详解》和《D3.js实现折线图的方法详解》这两篇文章，已经介绍过柱状图和折线图了。下面就来说说和这两种非常相似的图表——散点图和气泡图。有需要的朋友们可以参考学习。
散点图和气泡图的实现
还是和之前一样，我们先把简单的画图框架搭起来，添加SVG画布：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>散点图和气泡图</title> <style> .container { margin: 30px auto; width: 600px; height: 300px; border: 1px solid #000; } </style> </head> <body> <div> <svg></svg> </div> <script src="https://www.jb51.net/d3/d3.js"></script> <script> window.onload = function() { var width = 600, height = 300; // SVG画布边缘与图表内容的距离 var padding = { top: 50, right: 50, bottom: 50, left: 50 }; // 创建一个分组用来组合要画的图表元素 var main = d3.select('.container svg').append('g') // 给这个分组加上main类 .classed('main') // 设置该分组的transform属性 .attr('transform', "translate(" + padding.top + ',' + padding.left + ')'); }; </script> </body> </html>
散点图和气泡图虽然在展现意义上是不同的，但从技术实现的角度来讲，它们还是很类似的，都是由坐标轴和一个个的圆所组成的。
散点图
坐标轴的实现
为了实现真实的效果，散点图和气泡图我们使用不同的模拟数据。与折线图同理，散点图的各点的坐标的关系在坐标轴上的关系是连续的，所以它的x轴和y轴都使用线性比例尺（线性比例尺和序数比例尺的区别参见《D3.js实现柱状图的方法详解》）。
// 模拟数据 var dataset = [[161.2, 51.6], [167.5, 59.0], [159.5, 49.2], [157.0, 63.0], [155.8, 53.6], [170.0, 59.0], [159.1, 47.6], [166.0, 69.8], [176.2, 66.8], [160.2, 75.2], [172.5, 55.2], [170.9, 54.2], [172.9, 62.5], [153.4, 42.0], [160.0, 50.0], [147.2, 49.8], [168.2, 49.2], [175.0, 73.2], [157.0, 47.8], [167.6, 68.8], [159.5, 50.6], [175.0, 82.5], [166.8, 57.2], [176.5, 87.8], [170.2, 72.8], [174.0, 54.5], [173.0, 59.8], [179.9, 67.3], [170.5, 67.8], [160.0, 47.0], [154.4, 46.2], [162.0, 55.0], [176.5, 83.0], [160.0, 54.4], [152.0, 45.8], [162.1, 53.6], [170.0, 73.2], [160.2, 52.1], [161.3, 67.9], [166.4, 56.6], [168.9, 62.3], [163.8, 58.5], [167.6, 54.5], [160.0, 50.2], [161.3, 60.3], [167.6, 58.3], [165.1, 56.2], [160.0, 50.2], [170.0, 72.9], [157.5, 59.8], [167.6, 61.0], [160.7, 69.1], [163.2, 55.9], [152.4, 46.5], [157.5, 54.3], [168.3, 54.8], [180.3, 60.7], [165.5, 60.0], [165.0, 62.0], [164.5, 60.3], [156.0, 52.7], [160.0, 74.3], [163.0, 62.0], [165.7, 73.1], [161.0, 80.0], [162.0, 54.7], [166.0, 53.2], [174.0, 75.7], [172.7, 61.1], [167.6, 55.7], [151.1, 48.7], [164.5, 52.3], [163.5, 50.0], [152.0, 59.3], [169.0, 62.5], [164.0, 55.7], [161.2, 54.8], [155.0, 45.9], [170.0, 70.6], [176.2, 67.2], [170.0, 69.4], [162.5, 58.2], [170.3, 64.8], [164.1, 71.6], [169.5, 52.8], [163.2, 59.8], [154.5, 49.0], [159.8, 50.0], [173.2, 69.2], [170.0, 55.9], [161.4, 63.4], [169.0, 58.2], [166.2, 58.6], [159.4, 45.7], [162.5, 52.2], [159.0, 48.6], [162.8, 57.8], [159.0, 55.6], [179.8, 66.8], [162.9, 59.4], [161.0, 53.6], [151.1, 73.2], [168.2, 53.4], [168.9, 69.0], [173.2, 58.4], [171.8, 56.2], [178.0, 70.6], [164.3, 59.8], [163.0, 72.0], [168.5, 65.2], [166.8, 56.6], [172.7, 105.2], [163.5, 51.8], [169.4, 63.4], [167.8, 59.0], [159.5, 47.6], [167.6, 63.0], [161.2, 55.2], [160.0, 45.0], [163.2, 54.0], [162.2, 50.2], [161.3, 60.2], [149.5, 44.8], [157.5, 58.8], [163.2, 56.4], [172.7, 62.0], [155.0, 49.2], [156.5, 67.2], [164.0, 53.8], [160.9, 54.4], [162.8, 58.0], [167.0, 59.8], [160.0, 54.8], [160.0, 43.2], [168.9, 60.5], [158.2, 46.4], [156.0, 64.4], [160.0, 48.8], [167.1, 62.2], [158.0, 55.5], [167.6, 57.8], [156.0, 54.6], [162.1, 59.2], [173.4, 52.7], [159.8, 53.2], [170.5, 64.5], [159.2, 51.8], [157.5, 56.0], [161.3, 63.6], [162.6, 63.2], [160.0, 59.5], [168.9, 56.8], [165.1, 64.1], [162.6, 50.0], [165.1, 72.3], [166.4, 55.0], [160.0, 55.9], [152.4, 60.4], [170.2, 69.1], [162.6, 84.5], [170.2, 55.9], [158.8, 55.5], [172.7, 69.5], [167.6, 76.4], [162.6, 61.4], [167.6, 65.9], [156.2, 58.6], [175.2, 66.8], [172.1, 56.6], [162.6, 58.6], [160.0, 55.9], [165.1, 59.1], [182.9, 81.8], [166.4, 70.7], [165.1, 56.8], [177.8, 60.0], [165.1, 58.2], [175.3, 72.7], [154.9, 54.1], [158.8, 49.1], [172.7, 75.9], [168.9, 55.0], [161.3, 57.3], [167.6, 55.0], [165.1, 65.5], [175.3, 65.5], [157.5, 48.6], [163.8, 58.6], [167.6, 63.6], [165.1, 55.2], [165.1, 62.7], [168.9, 56.6], [162.6, 53.9], [164.5, 63.2], [176.5, 73.6], [168.9, 62.0], [175.3, 63.6], [159.4, 53.2], [160.0, 53.4], [170.2, 55.0], [162.6, 70.5], [167.6, 54.5], [162.6, 54.5], [160.7, 55.9], [160.0, 59.0], [157.5, 63.6], [162.6, 54.5], [152.4, 47.3], [170.2, 67.7], [165.1, 80.9], [172.7, 70.5], [165.1, 60.9], [170.2, 63.6], [170.2, 54.5], [170.2, 59.1], [161.3, 70.5], [167.6, 52.7], [167.6, 62.7], [165.1, 86.3], [162.6, 66.4], [152.4, 67.3], [168.9, 63.0], [170.2, 73.6], [175.2, 62.3], [175.2, 57.7], [160.0, 55.4], [165.1, 104.1], [174.0, 55.5], [170.2, 77.3], [160.0, 80.5], [167.6, 64.5], [167.6, 72.3], [167.6, 61.4], [154.9, 58.2], [162.6, 81.8], [175.3, 63.6], [171.4, 53.4], [157.5, 54.5], [165.1, 53.6], [160.0, 60.0], [174.0, 73.6], [162.6, 61.4], [174.0, 55.5], [162.6, 63.6], [161.3, 60.9], [156.2, 60.0], [149.9, 46.8], [169.5, 57.3], [160.0, 64.1], [175.3, 63.6], [169.5, 67.3], [160.0, 75.5], [172.7, 68.2], [162.6, 61.4], [157.5, 76.8], [176.5, 71.8], [164.4, 55.5], [160.7, 48.6], [174.0, 66.4], [163.8, 67.3] ]; // 创建x轴的比例尺 var xScale = d3.scale.linear() .domain([140, 190]) .range([0, width - padding.left - padding.right]); // 创建y轴的比例尺 var yScale = d3.scale.linear() .domain([40, 120]) .range([height - padding.top - padding.bottom, 0]); // 创建x轴 var xAxis = d3.svg.axis() .scale(xScale) .orient('bottom'); // 创建y轴 var yAxis = d3.svg.axis() .scale(yScale) .orient('left'); // 把x轴应用到对应的SVG元素上 main.append('g') .attr('class', 'axis') .attr('transform', 'translate(0,' + (height - padding.top - padding.bottom) + ')') .call(xAxis); // 把y轴应用到对应的SVG元素上 main.append('g') .attr('class', 'axis') .call(yAxis);