如何为d3.js中条形图中的每个条分配不同的颜色

Question

我正在尝试根据虚拟数据的 id 为条形图中的三个条形分配不同的颜色。但是由于某种原因我失败了，即使我创建了 colorArray 试图将其作为属性并附加到图表中。它应该相对容易，但不确定出了什么问题。请帮帮我！

const DUMMY_DATA = [
  { id: 'd1', level: 'High Happiness', value: 6.67 },
  { id: 'd2', level: 'Middle Happiness', value: 5.47 },
  { id: 'd3', level: 'Low Happiness', value: 4.35 },
  //{ id: 'd4', level: 'Germany', value: 6 },
];

const MARGINS = {top: 20, bottom: 10};
const CHART_WIDTH = 600; 
const CHART_HEIGHT = 400 - MARGINS.bottom - MARGINS.top; 

let selectedData = DUMMY_DATA;

const x = d3.scaleBand().rangeRound([0,CHART_WIDTH]).padding(0.1); 
const y = d3.scaleLinear().range([CHART_HEIGHT, 0]);
const colorArray = d3.scaleOrdinal().domain(["d1","d2","d3"]).range(["orange", "purple", "steelblue"]);

const chartContainer = d3.select("svg")
    .attr("width", CHART_WIDTH)
    .attr("height", CHART_HEIGHT + MARGINS.bottom + MARGINS.top);

    x.domain(DUMMY_DATA.map((d) => d.level));
    y.domain([0, d3.max(DUMMY_DATA, (d) => d.value) + 3] );


const chart = chartContainer.append("g");
chart.append("g")
    .call(d3.axisBottom(x).tickSizeOuter(0))
    .attr("transform", `translate(0, ${CHART_HEIGHT+10})`)
    .attr("color", "lighgray");
    
function renderChart(){
    chart
    .selectAll(".bar")
    .data(selectedData, data => data.id)
    .enter()
    .append("rect")
    .classed("bar", true)
    .attr("width", x.bandwidth())
    .attr("height", (data) => CHART_HEIGHT - y(data.value))
    .attr("x", (data) => x(data.level))
    .attr("y", (data) => y(data.value));
      
    chart.selectAll(".bar").data(selectedData, data => data.id).exit().remove();
    
    chart
    .selectAll(".label")
    .data(selectedData, data => data.id)
    .enter()
    .append("text")
    .text(data => data.value)
    .attr("x", data => x(data.level) + x.bandwidth()/2)
    .attr("y", data => y(data.value) - 20)
    .attr("text-anchor", "middle")
    .classed("label", true);
    
    chart.selectAll(".label").data(selectedData, data => data.id).exit().remove();
}

renderChart();

let unselectedIds = [];

const listItems =d3.select("#data")
.select("ul")
.selectAll("li")
.data(DUMMY_DATA)
.enter()
.append("li");

Answer 1

您需要将数据值传递给您的 colorArray 函数并使用 fill 应用它们：

chart.attr("fill", (data) => colorArray(data.id));

使用您的代码的工作示例：

const DUMMY_DATA = [
  { id: 'd1', level: 'High Happiness', value: 6.67 },
  { id: 'd2', level: 'Middle Happiness', value: 5.47 },
  { id: 'd3', level: 'Low Happiness', value: 4.35 },
];

const MARGINS = {top: 20, bottom: 10};
const CHART_WIDTH = 600; 
const CHART_HEIGHT = 400 - MARGINS.bottom - MARGINS.top; 

let selectedData = DUMMY_DATA;

const x = d3.scaleBand().rangeRound([0,CHART_WIDTH]).padding(0.1); 
const y = d3.scaleLinear().range([CHART_HEIGHT, 0]);
const colorArray = d3.scaleOrdinal().domain(["d1","d2","d3"]).range(["orange", "purple", "steelblue"]);

const chartContainer = d3.select("svg")
    .attr("width", CHART_WIDTH)
    .attr("height", CHART_HEIGHT + MARGINS.bottom + MARGINS.top);

    x.domain(DUMMY_DATA.map((d) => d.level));
    y.domain([0, d3.max(DUMMY_DATA, (d) => d.value) + 3] );


const chart = chartContainer.append("g");
chart.append("g")
    .call(d3.axisBottom(x).tickSizeOuter(0))
    .attr("transform", `translate(0, ${CHART_HEIGHT+10})`)
    .attr("color", "lighgray");
    
function renderChart(){
    chart
    .selectAll(".bar")
    .data(selectedData, data => data.id)
    .enter()
    .append("rect")
    .classed("bar", true)
    .attr("width", x.bandwidth())
    .attr("height", (data) => CHART_HEIGHT - y(data.value))
    .attr("x", (data) => x(data.level))
    .attr("y", (data) => y(data.value))
    // *********** Apply colors below ***********
    .attr("fill", (data) => colorArray(data.id));
      
    chart.selectAll(".bar").data(selectedData, data => data.id).exit().remove();
    
    chart
    .selectAll(".label")
    .data(selectedData, data => data.id)
    .enter()
    .append("text")
    .text(data => data.value)
    .attr("x", data => x(data.level) + x.bandwidth()/2)
    .attr("y", data => y(data.value) - 20)
    .attr("text-anchor", "middle")
    .classed("label", true)

    
    chart.selectAll(".label").data(selectedData, data => data.id).exit().remove();
}

renderChart();

let unselectedIds = [];

const listItems =d3.select("#data")
.select("ul")
.selectAll("li")
.data(DUMMY_DATA)
.enter()
.append("li");

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