How to add last stock price increase to the final label?

[winner106]

How to add stock price increase to the final label ( last Close / first Close - 1 ) * 100 ?

for example: AAPL(+200)

https://observablehq.com/@observablehq/plot-index-chart

[Fil]

Here is one possibility

Plot.plot({
  style: "overflow: visible;",
  y: {
    type: "log",
    grid: true,
    label: "↑ Change in price (%)",
    tickFormat: (
      (f) => (x) =>
        f((x - 1) * 100)
    )(d3.format("+d"))
  },
  marks: [
    Plot.ruleY([1]),
    Plot.lineY(
      stocks,
      Plot.normalizeY({
        x: "Date",
        y: "Close",
        stroke: "Symbol"
      })
    ),
    Plot.text(
      stocks,
      Plot.selectLast(
        Plot.map(
          {
            text: (data) =>
              Plot.valueof(
                data,
                (d) => `${d.Symbol}\n${format( (d["Close"] / data[0].Open - 1))}`
              )
          },
          Plot.normalizeY({
            x: "Date",
            y: "Close",
            z: "Symbol",
            text: (d) => d,
            textAnchor: "start",
            dx: 3
          })
        )
      )
    )
  ]
})

with

format = d3.format("+.1%")

[winner106]

This is indeed challenging for me. Transforms are difficult to master. Thank you very much for your guidance.