Function buildHeatmapData

packages/core/src/chart/index.ts:260–296

(rows: Record<string, unknown>[], spec: ChartSpec)

}

function buildHeatmapData(rows: Record<string, unknown>[], spec: ChartSpec): HeatmapChartRenderData {
  const xField = spec.encoding.x!
  const yField = spec.encoding.y!
  const valueField = spec.encoding.value!
  const xLabels: string[] = []
  const yLabels: string[] = []
  const xIndex = new Map<string, number>()
  const yIndex = new Map<string, number>()
  const values = new Map<string, number>()

  for (const row of rows) {
    const xLabel = toLabel(row[xField])
    const yLabel = toLabel(row[yField])
    let xi = xIndex.get(xLabel)
    if (xi === undefined) {
      xi = xLabels.length
      xIndex.set(xLabel, xi)
      xLabels.push(xLabel)
    }
    let yi = yIndex.get(yLabel)
    if (yi === undefined) {
      yi = yLabels.length
      yIndex.set(yLabel, yi)
      yLabels.push(yLabel)
    }
    const key = `${xi}:${yi}`
    values.set(key, (values.get(key) ?? 0) + toNumber(row[valueField], valueField))
  }

  const data: Array<[number, number, number]> = []
  for (const [key, value] of values.entries()) {
    const [x, y] = key.split(':').map(Number)
    data.push([x, y, value])
  }

  return { xLabels, yLabels, data }
}

export function buildChartPayload(
  rows: Record<string, unknown>[],