Function buildLineData

packages/core/src/chart/index.ts:216–258

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

}

function buildLineData(rows: Record<string, unknown>[], spec: ChartSpec): LineChartRenderData {
  const xField = spec.encoding.x!
  const yField = spec.encoding.y!
  const seriesField = spec.encoding.series

  if (!seriesField) return aggregateByLabel(rows, xField, yField)

  assertFieldExists(rows, seriesField)
  const labels: string[] = []
  const labelIndex = new Map<string, number>()
  const seriesNames: string[] = []
  const seriesIndex = new Map<string, number>()
  const matrix: number[][] = []

  for (const row of rows) {
    const label = toLabel(row[xField])
    const seriesName = toLabel(row[seriesField])
    let xIndex = labelIndex.get(label)
    if (xIndex === undefined) {
      xIndex = labels.length
      labelIndex.set(label, xIndex)
      labels.push(label)
      for (const values of matrix) values.push(0)
    }

    let sIndex = seriesIndex.get(seriesName)
    if (sIndex === undefined) {
      sIndex = seriesNames.length
      seriesIndex.set(seriesName, sIndex)
      seriesNames.push(seriesName)
      matrix.push(Array(labels.length).fill(0))
    }

    matrix[sIndex][xIndex] += toNumber(row[yField], yField)
  }

  const series = seriesNames.map((name, index) => ({ name, values: matrix[index] }))
  return {
    labels,
    values: series[0]?.values ?? [],
    series,
  }
}

function buildHeatmapData(rows: Record<string, unknown>[], spec: ChartSpec): HeatmapChartRenderData {
  const xField = spec.encoding.x!