google图表时间线按ID分组的条形图颜色

<script type="text/javascript" src="https://www.gstatic.com/charts/loader.js"></script>

google.charts.load('current', {'packages':['corechart']});
google.charts.setOnLoadCallback(drawChart);

function drawChart() {
  var data = google.visualization.arrayToDataTable([
    ['ID', 'Start', 'End', 'Category'],
    ['A', new Date(2021, 0, 1), new Date(2021, 0, 10), 'Cat1'],
    ['B', new Date(2021, 0, 3), new Date(2021, 0, 8), 'Cat2'],
    ['A', new Date(2021, 0, 12), new Date(2021, 0, 20), 'Cat1'],
    ['B', new Date(2021, 0, 15), new Date(2021, 0, 25), 'Cat2']
  ]);

  var options = {
    title: '按ID分组的条形图',
    legend: { position: 'none' },
    series: {
      0: { color: '#3366CC' }, // ID为'A'的颜色
      1: { color: '#DC3912' }  // ID为'B'的颜色
    }
  };

  var chart = new google.visualization.ColumnChart(document.getElementById('chart_div'));
  chart.draw(data, options);
}

<div id="chart_div" style="width: 900px; height: 500px;"></div>