Function aggregateByLabel

packages/core/src/chart/index.ts:189–214

(
  rows: Record<string, unknown>[],
  labelField: string,
  valueField: string
)

}

function aggregateByLabel(
  rows: Record<string, unknown>[],
  labelField: string,
  valueField: string
): {
  labels: string[]
  values: number[]
} {
  const labels: string[] = []
  const indexByLabel = new Map<string, number>()
  const values: number[] = []

  for (const row of rows) {
    const label = toLabel(row[labelField])
    let index = indexByLabel.get(label)
    if (index === undefined) {
      index = labels.length
      indexByLabel.set(label, index)
      labels.push(label)
      values.push(0)
    }
    values[index] += toNumber(row[valueField], valueField)
  }

  return { labels, values }
}

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