如何在 D3 v6 中调整条形图的 y 轴比例？

Question

I am trying to create a bar chart right now, but currently I am facing a problem that my bars are not properly scaled comparing to the data. Here is my code in D3:

var third_width = 1000;
var third_height = 450;
var third_padding = 30;
    
var third_countries = ["Australia", "Austria", "Denmark", "Netherlands","New Zealand", "Norway", "Sweden", "UK","USA","Japan","Poland","Finland","Italy","France","Belgium"]
var third_data = [102, 39, 81, 50, 61, 79, 81, 77, 59, 64, 56, 65, 57, 85, 50];

var third_xScale = d3.scaleBand()
                     .domain(d3.range(third_data.length))
                     .rangeRound([third_padding ,third_width])
                     .paddingInner(0.1);

var third_yScale = d3.scaleLinear()
                     .domain([0, d3.max(third_data)])
                     .range([third_height - third_padding, third_padding]);

var third_xAxis = d3.axisBottom()
                    .scale(third_xScale).tickFormat(function(i) {return third_countries[i];})

var third_yAxis = d3.axisLeft()
                    .scale(third_yScale).ticks(5);

var third_svg = d3.select("#chart3")
                  .append("svg")
                  .attr("width", third_width)
                  .attr("height", third_height);

third_svg.selectAll("rect")
    .data(third_data)
    .enter()
    .append("rect")
    .attr("x", function(d, i) {
       return third_xScale(i);
    })
    .attr("y", function(d) {
       return third_height - third_padding - third_yScale(d);
    })
    .attr("width", third_xScale.bandwidth())
    .attr("height", function(d) {
       return third_yScale(d);
    })
    .attr("fill", function(d) {
       return "rgb(0, 0, " + Math.round(d * 10) + ")";
    });

//Create "Food waste per capita (kg/year)" on Y Axis
third_svg.append('text')
        .attr('x', 5)
        .attr('y', 20)
        .attr('text-anchor', 'left')
        .style('font-family', 'Helvetica')
        .style('font-size', 'small')
        .text('Food waste per capita (kg/year)');

third_svg.append("g")
         .attr("class", "axis")
         .attr("transform", "translate(" + third_padding + ",0)")
         .call(third_yAxis);



third_svg.append("g")
         .attr("class", "axis")
         .attr("transform", "translate(0,"+ (third_height - third_padding) + ")")
         .call(third_xAxis);

And you could see the result on this image, in which the first bar indicates a value of nearly 10 rather than 102:

Could you please help me to know how to fix the axes in this case, so that the value in y-axis could be lined up?

Thank you!

Answer 1

The direction of your Y scale (downside-up) is opposite to the SVG's (upside-down).

It can be solved by switching the values of y and height attributes for the <rect> s:

third_svg.selectAll("rect")
  .data(third_data)
  .enter()
  .append("rect")
  .attr('y', d => third_yScale(d))
  .attr("height", d => third_height - third_padding - third_yScale(d))
  ...

See it's working in the snippet:

 const third_width = 1000; const third_height = 450; const third_padding = 30; const third_countries = ["Australia", "Austria", "Denmark", "Netherlands","New Zealand", "Norway", "Sweden", "UK","USA","Japan","Poland","Finland","Italy","France","Belgium"] const third_data = [102, 39, 81, 50, 61, 79, 81, 77, 59, 64, 56, 65, 57, 85, 50]; const third_xScale = d3.scaleBand().domain(d3.range(third_data.length)).rangeRound([third_padding,third_width]).paddingInner(0.1); const third_yScale = d3.scaleLinear().domain([0, d3.max(third_data)]).range([third_height - third_padding, third_padding]); const third_xAxis = d3.axisBottom().scale(third_xScale).tickFormat(function(i) {return third_countries[i];}) const third_yAxis = d3.axisLeft().scale(third_yScale).ticks(5); const third_svg = d3.select("#chart3").append("svg").attr("width", third_width).attr("height", third_height); third_svg.selectAll("rect").data(third_data).enter().append("rect").attr("x", (d, i) => third_xScale(i)).attr('y', d => third_yScale(d)).attr("height", d => third_height - third_padding - third_yScale(d)).attr("width", third_xScale.bandwidth()).attr("fill", d => `rgb(0, 0, ${d * 2})`); //Create "Food waste per capita (kg/year)" on Y Axis third_svg.append('text').attr('x', 5).attr('y', 20).attr('text-anchor', 'left').style('font-family', 'Helvetica').style('font-size', 'small').text('Food waste per capita (kg/year)'); third_svg.append("g").attr("class", "axis").attr("transform", "translate(" + third_padding + ",0)").call(third_yAxis); third_svg.append("g").attr("class", "axis").attr("transform", "translate(0,"+ (third_height - third_padding) + ")").call(third_xAxis);

 <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/6.7.0/d3.min.js"></script> <div id="chart3" />