Peak Value Annotation

import { Chart } from '@antv/g2';

const chart = new Chart({ container: 'container' });

const transform = [
  {
    type: 'selectY',
    groupBy: 'color',
    selector: 'max',
  },
];

chart.options({
  type: 'view',
  autoFit: true,
  data: [
    { month: 'Jan', city: 'Tokyo', temperature: 7 },
    { month: 'Jan', city: 'London', temperature: 3.9 },
    { month: 'Feb', city: 'Tokyo', temperature: 6.9 },
    { month: 'Feb', city: 'London', temperature: 4.2 },
    { month: 'Mar', city: 'Tokyo', temperature: 9.5 },
    { month: 'Mar', city: 'London', temperature: 5.7 },
    { month: 'Apr', city: 'Tokyo', temperature: 14.5 },
    { month: 'Apr', city: 'London', temperature: 8.5 },
    { month: 'May', city: 'Tokyo', temperature: 18.4 },
    { month: 'May', city: 'London', temperature: 11.9 },
    { month: 'Jun', city: 'Tokyo', temperature: 21.5 },
    { month: 'Jun', city: 'London', temperature: 15.2 },
    { month: 'Jul', city: 'Tokyo', temperature: 25.2 },
    { month: 'Jul', city: 'London', temperature: 17 },
    { month: 'Aug', city: 'Tokyo', temperature: 26.5 },
    { month: 'Aug', city: 'London', temperature: 16.6 },
    { month: 'Sep', city: 'Tokyo', temperature: 23.3 },
    { month: 'Sep', city: 'London', temperature: 14.2 },
    { month: 'Oct', city: 'Tokyo', temperature: 18.3 },
    { month: 'Oct', city: 'London', temperature: 10.3 },
    { month: 'Nov', city: 'Tokyo', temperature: 13.9 },
    { month: 'Nov', city: 'London', temperature: 6.6 },
    { month: 'Dec', city: 'Tokyo', temperature: 9.6 },
    { month: 'Dec', city: 'London', temperature: 4.8 },
  ],
  encode: { x: 'month', y: 'temperature', color: 'city' },
  scale: { x: { range: [0, 1] }, y: { nice: true } },
  axis: { y: { labelFormatter: (d) => d + '°C' } },
  children: [
    { type: 'line', encode: { shape: 'smooth' } },
    {
      type: 'text',
      encode: {
        x: 'month',
        y: 'temperature',
        text: (d) => `峰值：${d.temperature}`,
      },
      transform,
      style: {
        fill: 'orange',
        fontSize: 16,
        dy: -15,
      },
      tooltip: false,
    },
    {
      type: 'point',
      encode: { x: 'month', y: 'temperature' },
      transform,
      tooltip: false,
    },
  ],
});

chart.render();