d3.js v4，在气泡图上为气泡添加文本标签 [英] d3.js v4, adding text labels to bubbles on a bubble chart

问题描述

我正在构建一个气泡图。图表正好显示我的喜好。我遇到的唯一问题是让文字出现在每个泡泡的中间。

I'm building a bubble chart. The chart is appearing exactly how I'd like. The only issue I have been having is getting text to appear in the middle of each bubble.

文字根本没有出现，我尝试了几个选项来实现它。当我检查页面时，每个圆圈内都有一个文本元素。但是，该元素不会出现在页面上，尽管它嵌套在每个圆圈内。我在下面粘贴我的代码。非常感谢所有帮助。

Text is not appearing at all and I have tried several options to get it there. When I inspect the page, inside of each circle there is a text element. However, the element does not appear on the page, although it is nested inside of each circle. I am pasting my code below. All help is greatly appreciated.

let width = 600;
let height = 600;

let maxRadius = d3.max(data, (data) => { return data.PercentHomeless; })
let minRadius = d3.min(data, (data) => { return data.PercentHomeless; })

let svg = d3.selectAll('section')
           .append('svg')
           .attr('height', height)
           .attr('width', width)
           .append('g')
           .attr('transform', 'translate(0, 0)')

let colors = d3.scaleOrdinal(d3.schemePaired);

let simulation = d3.forceSimulation()
                  .force('x', d3.forceX(width/2).strength(0.5))
                  .force('y', d3.forceY(height/2).strength(0.5))
                  .force('collide', d3.forceCollide((data) => { return r(data.PercentHomeless) + 1.5; }))

let r = d3.scaleSqrt()
          .domain([minRadius, maxRadius])
          .range([15,75])

let circles = svg.selectAll('circles')
              .data(data)
              .enter()
              .append('circle')
              .attr('fill', (data) => { return colors(data.State); })
              .attr('r', (data) => { return r(data.PercentHomeless); })

circles.append('text')
  .attr("dy", ".3em")
  .attr("dx", -10)
  .attr("text-anchor", "middle")
  .text((data) => { return data.State; })
  .attr('color', 'black')
  .attr('font-size', 15)


let ticked = () => {
  circles
  .attr('cx', (data) => { return data.x })
  .attr('cy', (data) => { return data.y })
}

simulation.nodes(data)
  .on('tick', ticked)


});

推荐答案

在SVG中，< circle> 不是一个容器元素，也就是说， 不能将文本附加到圈子中。当您检查页面时，您在圆圈元素中看到文本的事实没有区别：它们不会被渲染。

In SVGs, <circle> is not a container element, that is, you cannot append texts to circles. The fact that you see the texts inside the circle elements when you inspect the page makes no difference: they will not be rendered.

解决方案：为文本创建单独的选择：

Solution: create a separate selection for the texts:

let texts = svg.selectAll(null)
    .data(data)
    .enter()
    .append('text')
    .text(d => d.State)
    .attr('color', 'black')
    .attr('font-size', 15)

并在<$中重新定位它们c $ c>勾选功能（根据您的需要更改其x和y位置）：

And reposition them in the ticked function (change their x and y positions according to your needs):

let ticked = () => {
    circles.attr('cx', (data) => {
            return data.x
        })
        .attr('cy', (data) => {
            return data.y
        });

    texts.attr('x', (data) => {
            return data.x
        })
        .attr('y', (data) => {
            return data.y
        });
}

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