如何在圆环图中的扇区之间缩进？

问题描述

这是我的代码：

const innerRadius = 40;
const colorSmooth = 300; //smooth transition of colors (resolution)
const innerText = "Chart";

// values in perсents
var percentsGreat = 50;
var percentsGood = 20;
var percentsnormal = 20;
var percentsBad = 10;

// "start","end" arcs colors pair per value
var greatStartColor = "#FFE39C";
var greatEndColor = "#FFBA9C";
var goodStartColor = "#6FCF97";
var goodEndColor = "#66D2EA";
var normalStartColor = "#BC9CFF";
var normalEndColor = "#8BA4F9";
var badStartColor = "#919191";
var badEndColor = "#3D4975";


// define the workspace and set the origin to its center
var svg = d3.select("svg"),width = svg.attr("width"),height = svg.attr("height"),g = svg.append("g").attr("transform","translate(" + width / 2 + "," + height / 2 + ")");

var radius = d3.min([width,height]) / 2;

var arc = d3.arc()
  .innerRadius(radius - innerRadius)
  .outerRadius(radius)
  .startAngle(function(d) {
    return d;
  })
  .endAngle(function(d) {
    return d + dblpi / colorSmooth * 1.2;
  }); // 1.2 to block artifacts on the transitions

var great = colorSmooth / 100 * percentsGreat;
var good = colorSmooth / 100 * percentsGood + great;
var normal = colorSmooth / 100 * percentsnormal + good;
var bad = colorSmooth / 100 * percentsBad + normal;

var dblpi = 2 * Math.PI;

var color = d3.scaleLinear()
  .domain([0,great,good,normal,bad
  ])
  .range([greatStartColor,greatEndColor,goodStartColor,goodEndColor,normalStartColor,normalEndColor,badStartColor,badEndColor
  ])
  .interpolate(d3.interpolateRgb)

g.selectAll("path")
  .data(d3.range(0,dblpi,dblpi / colorSmooth))
  .enter()
  .append("path")
  .attr("d",arc)
  .style("fill",function(d,i) {
    return color(i);
  });

g.append("text")
  .attr("class","percent-score")
  .attr("dy",".35em") // align the text to the center of the chart
  .attr("text-anchor","middle")
  .text(innerText);

// svg.attr("stroke","white")
//  .style("stroke-width","2px");

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js"></script>
<svg width="500" height="400"></svg>

如何在扇区之间缩进？就像这张图：

我找到了一个没有渐变的图表解决方案（最后两行），但它不适用于渐变。

解决方法

惯用的 D3 使用 padAngle：

垫角被转换为分隔相邻圆弧的固定线性距离，定义为 padRadius * padAngle。从弧的起点和终点减去这个距离。

但是，由于您创建渐变的方式很奇怪（使用多个路径），这里我使用阈值比例来比较索引：

.padAngle((_,i) => color2(i) === color2(i + 1) ? 0 : 1)

即便如此，您也会发现以弧度表示的角度不正确。也就是说，我建议您改变方法（每个类别只使用一个路径）。

这是您的更改代码：

const innerRadius = 40;
const colorSmooth = 300; //smooth transition of colors (resolution)
const innerText = "Chart";

// values in perсents
var percentsGreat = 50;
var percentsGood = 20;
var percentsNormal = 20;
var percentsBad = 10;

// "start","end" arcs colors pair per value
var greatStartColor = "#FFE39C";
var greatEndColor = "#FFBA9C";
var goodStartColor = "#6FCF97";
var goodEndColor = "#66D2EA";
var normalStartColor = "#BC9CFF";
var normalEndColor = "#8BA4F9";
var badStartColor = "#919191";
var badEndColor = "#3D4975";


// define the workspace and set the origin to its center
var svg = d3.select("svg"),width = svg.attr("width"),height = svg.attr("height"),g = svg.append("g").attr("transform","translate(" + width / 2 + "," + height / 2 + ")");

var radius = d3.min([width,height]) / 2;

var arc = d3.arc()
  .innerRadius(radius - innerRadius)
  .outerRadius(radius)
  .padAngle((_,i) => color2(i) === color2(i + 1) ? 0 : 1)
  .startAngle(function(d) {
    return d;
  })
  .endAngle(function(d) {
    return d + dblpi / colorSmooth * 1.2;
  }); // 1.2 to block artifacts on the transitions

var great = colorSmooth / 100 * percentsGreat;
var good = colorSmooth / 100 * percentsGood + great;
var normal = colorSmooth / 100 * percentsNormal + good;
var bad = colorSmooth / 100 * percentsBad + normal;

var dblpi = 2 * Math.PI;

var color = d3.scaleLinear()
  .domain([0,great,good,normal,bad
  ])
  .range([greatStartColor,greatEndColor,goodStartColor,goodEndColor,normalStartColor,normalEndColor,badStartColor,badEndColor
  ])
  .interpolate(d3.interpolateRgb);

const color2 = d3.scaleThreshold()
  .domain([great,bad])
  .range(d3.range(6));

g.selectAll("path")
  .data(d3.range(0,dblpi,dblpi / colorSmooth))
  .enter()
  .append("path")
  .attr("d",arc)
  .style("fill",function(d,i) {
    return color(i);
  });

g.append("text")
  .attr("class","percent-score")
  .attr("dy",".35em") // align the text to the center of the chart
  .attr("text-anchor","middle")
  .text(innerText);

// svg.attr("stroke","white")
//  .style("stroke-width","2px");

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/5.7.0/d3.min.js"></script>
<svg width="500" height="400"></svg>

,

将 .attr("stroke","white") 和 .attr("stoke-width","5px") 添加到弧定义将在弧之间添加缩进扇区（空格）。

g.selectAll("path")
      .data(d3.range(0,dblpi / colorSmooth))
      .enter()
      .append("path")
      .attr("d",arc)
      .attr("stroke","white")
      .attr("stoke-width","5px")
      .style("fill",i) {
        return color(i);
      });

注意：您正在使用多个颜色范围来创建渐变效果，这将导致为每个颜色值生成多个弧线，从而生成此 https://codepen.io/mont8593/pen/mdOBLdd

您可以参考 Adding gradient to 3rd party solid color donut chart 在圆环图中实现渐变。