D3.js 更自由的条形图

一、添加一个矩形

//Width and height
var w = 500;
var h = 100;

var dataset = [ 5, 10, 13, 19, 21, 25, 22, 18, 15, 13,11, 12, 15, 20, 18, 17, 16, 18, 23, 25 ];

//创建SVG元素
var svg = d3.select("body")
    .append("svg")
    .attr("width", w)
    .attr("height", h);

svg.selectAll("rect")
    .data(dataset)
    .enter()
    .append("rect")
    .attr("x", 0)
    .attr("y", 0)
    .attr("width", 20)
    .attr("height", 100);

二、添加多条矩形

//Width and height
var w = 500;
var h = 100;

var dataset = [ 5, 10, 13, 19, 21, 25, 22, 18, 15, 13,11, 12, 15, 20, 18, 17, 16, 18, 23, 25 ];

//创建SVG元素
var svg = d3.select("body")
    .append("svg")
    .attr("width", w)
    .attr("height", h);

svg.selectAll("rect")
    .data(dataset)
    .enter()
    .append("rect")
    .attr("x", function(d, i) {
        return i * 21; //Bar width of 20 plus 1 for padding
    })
    .attr("y", 0)
    .attr("width", 20)
    .attr("height", 100);

三、均匀的添加条-定条宽

　　除的方式(i * (w / dataset.length);)作为条和间隙的总宽度，在设置固定宽度小于总宽度，这时就会自然生成一个空白间隙

　　一句话：条的宽度固定，总宽-条宽=空白宽。空白宽取决于总宽，总宽取决于计算表达式(w / dataset.length）

//Width and height
var w = 500;
var h = 100;
var barPadding = 1;

var dataset = [ 5, 10, 13, 19, 21, 25, 22, 18, 15, 13,11, 12, 15, 20, 18, 17, 16, 18, 23, 25 ];

//创建SVG元素
var svg = d3.select("body")
    .append("svg")
    .attr("width", w)
    .attr("height", h);

svg.selectAll("rect")
    .data(dataset)
    .enter()
    .append("rect")
    .attr("x", function(d, i) {
        return i * (w / dataset.length);
    })
    .attr("y", 0)
    .attr("width", 20)
    .attr("height", 100);

 四、均匀的添加条-定间隙宽

　　一句话：间隙的宽度固定，总宽-空白宽=条宽。条宽取决于总宽（w / dataset.length - barPadding），总宽取决于计算表达式(w / dataset.length）

//Width and height
var w = 500;
var h = 100;
var barPadding = 1;

var dataset = [ 5, 10, 13, 19, 21, 25, 22, 18, 15, 13,11, 12, 15, 20, 18, 17, 16, 18, 23, 25 ];

//Create SVG element
var svg = d3.select("body")
    .append("svg")
    .attr("width", w)
    .attr("height", h);

svg.selectAll("rect")
    .data(dataset)
    .enter()
    .append("rect")
    .attr("x", function(d, i) {
        return i * (w / dataset.length);
    })
    .attr("y", 0)
    .attr("width", w / dataset.length - barPadding)
    .attr("height", 100);