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Area plot not working on single point despite strokeLinecap: square

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难度
3/5
预计耗时
1-2 天
新手友好度
55/100
Issue 类型
缺陷
描述清晰度
基本清楚
活跃度
活跃
技术栈
d3, javascript
领域
data-visualization

调研方向

从 area mark API 文档开始，使用带有 gaps 和 strokeLinecap: "square" 的 Plot.areaY 复现 Observable notebook 示例。检查生成的 SVG 路径，并将其与报告中展示的 CSS workaround 进行比较。当单点 area segment 使用文档所述选项即可被明显渲染，且无需额外样式时，即视为完成。

由索引模型根据 Issue 内容生成。

描述

documentation
Describing the bug

As the title implies either I didn't understand the docs for this use case or there is a bug:

Excerpt from the API docs on area marks:

The area mark supports curve options to control interpolation between points. If any of the x1, y1, x2, or y2 values are invalid (undefined, null, or NaN), the baseline and topline will be interrupted, resulting in a break that divides the area shape into multiple segments. (See d3-shape’s area.defined for more.) If an area segment consists of only a single point, it may appear invisible unless rendered with rounded or square line caps. In addition, some curves such as cardinal-open only render a visible segment if it contains multiple points.

Expected behavior

If my plot contains gaps which creates single points, I don't need to do anything else but define the mark option strokeLinecap: 'square' so that I still see an area rendered at this data point.

Steps how to reproduce

Here is my minimal working example in an Observable notebook

data = [
    {
        "time": 2009,
        "value": 74.08,
        "lowerBounds": 73.25,
        "upperBounds": 74.89,
        "age": "A0000",
        "sex": 0
    }, {
        "time": 2010,
        "value": 75.17,
        "lowerBounds": 74.37,
        "upperBounds": 75.96,
        "age": "A0000",
        "sex": 0
    }, {
        "time": 2011,
        "value": null
    }, {
        "time": 2012,
        "value": 75.95,
        "lowerBounds": 75.06,
        "upperBounds": 76.82,
        "age": "A0000",
        "sex": 0
    }, {
        "time": 2016,
        "value": null
    }, {
        "time": 2022,
        "value": 66.4,
        "lowerBounds": 63.23,
        "upperBounds": 69.44,
        "age": "A0000",
        "sex": 0
    }, {
        "time": 2023,
        "value": 67.98,
        "lowerBounds": 66.23,
        "upperBounds": 69.68,
        "age": "A0000",
        "sex": 0
    }
]

Plot.plot({
  x: {
    interval: 1,
    tickFormat: ''
  },
  y: {
    label: 'Proportion of people who have had a dental check-up in the last 12 months',
    tickFormat: d => `${d} %`
  },
  inset: 8,
  grid: true,
  marks: [
    Plot.areaY(data, {x: "time", y1: "lowerBounds", y2: "upperBounds", fill: "#DD1A1E", fillOpacity: 0.2, strokeLinecap: "square"}),
    Plot.lineY(data, {x: "time", y: "value", stroke: "#DD1A1E", marker: "circle"})
  ]
})

This is what it looks like at this point in time:

Screenshot_20240906_Observable_plot_area_mark_bug

Only after adding styles to the area (SVG <path> Element) do I see the area for a single point. Is this the desired method?

Screenshot_20240906_Observable_plot_area_mark_css_trick

主要语言
HTML
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