Simple bar chart with multiple series

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1

How can I create bar chart that has multiple series?

Eg. I would like to have for each date (those date numbers are hourly points eg. ‘2024-03-05 10:00:00’) four bars:

  1. this course - started
  2. this course - submitted
  3. other courses - started
  4. other course - submitted

Or, even easier and more general, if i have two measurements (e.g. y1 and y2 for some date point) how can I create two bars, one for y1 and one for y2 (I don’t want stacked bars)

Thanks.

2

One way you could do it is by faceting, which we can use to provide “inner x axis” in this case. Here I set the normal x channel as the category/type combination, and set the fx channel (the “outer” x axis) to the date.

plot = Plot.plot({
  x: { ticks: [] },
  y: { grid: true },
  fx: { type: "utc" },
  color: { legend: true },
  width,
  marks: [
    Plot.barY(data, {
      x: (d) => `${d.category} - ${d.type}`,
      y: "cnt",
      fx: "date",
      fill: (d) => `${d.category} - ${d.type}`,
      tip: true
    }),
    Plot.ruleY([0])
  ]
})

Another thing you could explore is using multiple Plot.barY marks, one for each bar you want to draw. That has difficulties with bars overlapping though.

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