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Documentation for Layer Cake v10, before Svelte 5 runes. Current docs at layercake.graphics

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Histogram (variable bins)

40 bins
1.6
6.56
11.52
16.48
21.44
26.4
0
200
400

Histogram using Layer Cake's bin function. Each bin has x0 and x1 edges, so the x accessor is both of them and each column spans its bin. Drag the slider to change how many bins there are.

This is the server-side rendered version. ssr and percentRange on <LayerCake> put the scales in percentages, so the chart renders before the browser measures it. The axes are HTML components and the marks sit in a <ScaledSvg> that stretches to fit its box.

  • +page.svelte
  • ./_components/Column.svelte
  • ./_components/AxisX.percent-range.html.svelte
  • ./_components/AxisY.percent-range.html.svelte
  • ./_modules/calcThresholds.js
  • ./_data/unemployment.js
<script>
  import { LayerCake, ScaledSvg, Html, bin, takeEvery } from 'layercake';

  import { scaleBand } from 'd3-scale';
  import { format } from 'd3-format';

  import Column from './_components/Column.svelte';
  import AxisX from './_components/AxisX.percent-range.html.svelte';
  import AxisY from './_components/AxisY.percent-range.html.svelte';

  import calcThresholds from './_modules/calcThresholds.js';

  import data from './_data/unemployment.js';

  const f = format('.2f');

  // Each bin has x0 and x1 edges, so the x accessor is both and each column spans them
  const xKey = ['x0', 'x1'];
  const yKey = 'length';

  let binCount = $state(40);

  /** @type {[number, number]} */
  const domain = [Math.min(...data), Math.max(...data)];

  let thresholds = $derived(calcThresholds(domain, binCount));
  let slimThresholds = $derived(takeEvery(thresholds, 5));

  let binnedData = $derived(
    bin(data, d => d, {
      domain,
      thresholds
    })
  );
</script>

<div class="input-container" style="position: absolute;right:10px;z-index: 9;">
  <input style="margin:0;" type="range" min="4" max="100" step="4" bind:value={binCount} />
  <span
    class="counter-container"
    style="display:inline-block;vertical-align:top;width: 70px;text-align:right;"
    >{binCount} bins</span
  >
</div>

<div class="chart-container">
  <LayerCake
    ssr
    percentRange
    padding={{ top: 20, right: 5, bottom: 20, left: 30 }}
    x={xKey}
    y={yKey}
    xDomain={thresholds}
    xScale={scaleBand().paddingInner(0)}
    yDomain={[0, null]}
    data={binnedData}
  >
    <Html>
      <AxisX gridlines={false} showBaseline ticks={slimThresholds} format={d => String(+f(d))} />
      <AxisY gridlines={false} ticks={3} />
    </Html>
    <ScaledSvg>
      <Column fill="#fff" stroke="#000" strokeWidth={1} />
    </ScaledSvg>
  </LayerCake>
</div>

<style>
  /* Give the wrapper a width and height. LayerCake fills it. */
  .chart-container {
    width: 100%;
    height: 250px;
  }
  input {
    height: auto;
  }
</style>