具有 0 个数据的 D3 圆环图

Question

I have a D3 donut chart I've created with this code:

  var svg = d3.select('#chart-cont-2')
    .append('svg')
      .attr('width', width)
      .attr('height', height)

  var g = svg.append('g')
    .attr("transform", "translate(" + width / 2 + "," + height / 2 + ")")

  var chart_g = g.append('g')
    .attr('class', 'chart')

  var text_g = g.append('g')
    .attr('class', 'text')

  var color = d3.scaleOrdinal()
    .domain(dataset)
    .range(['rgba(2, 168, 150, 1)', 'rgba(237, 109, 0, 1)'])

  var pie = d3.pie()
    .value((d) => d.value)

  var arc = d3.arc()
    .innerRadius(87)
    .outerRadius(77)

  chart_g.selectAll('.part')
    .data(pie(d3.entries(dataset)))
    .enter()
    .append('path')
      .attr('d', arc)
      .attr('fill', (d, i) => color(i))

There may be times when the dataset is empty. Is there a way I can have an rgba(2, 168, 150, 1) color donut chart when there is no data present and then switch to my coded donut chart when there is data present?

EDIT : My dataset is an object:

{a: 0, b: 0}

When both values are 0, I would like the donut chart in the color of rgba(2, 168, 150, 1) to show up.

Answer 1

Yes, you just need to know that dataset is not empty. Define an array of possible colors, before you pass it to .range .

Example:

var colorsRange = dataset && dataset.length ? ['rgba(2, 168, 150, 1)', 'rgba(237, 109, 0, 1)'] : ['rgba(2, 168, 150, 1)'];

var color = d3.scaleOrdinal()
   .domain(dataset)
   .range(colorsRange);