Google Chart：获取仪表板中条形图的列数

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

function drawChart() {
  var data = google.visualization.arrayToDataTable([
    ['date', 'tag_id'],
    [new Date('2016-09-29 06:47:47'), '04:0f'],
    [new Date('2016-09-29 14:48:42'), '04:0f'],
    [new Date('2016-10-29 06:47:47'), '99:9n'],
    [new Date('2016-11-29 06:48:42'), '05:m8'],
  ]);

  var formatDate = new google.visualization.DateFormat({pattern: 'MMMM'});

  var dataGroup = google.visualization.data.group(
    data,

    // group by column
    [{
      column: 0,
      label: 'Month',
      modifier: function (val) {
        return formatDate.formatValue(val);
      },
      type: 'string'
    }],

    // agg columns
    [{
      aggregation: google.visualization.data.count,
      column: 1,
      label: 'Tag Count',
      type: 'number'
    }]
  );

  var table = new google.visualization.Table(document.getElementById('chart_div'));
  table.draw(dataGroup);
}

<script src="https://www.gstatic.com/charts/loader.js"></script>
<div id="chart_div"></div>

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

function drawChart() {
  var data = google.visualization.arrayToDataTable([
    ['date', 'tag_id'],
    [new Date('2016-09-29 06:47:47'), '04:0f'],
    [new Date('2016-09-29 14:48:42'), '04:0f'],
    [new Date('2016-10-29 06:47:47'), '99:9n'],
    [new Date('2016-11-29 06:48:42'), '05:m8'],
  ]);

  var formatDate = new google.visualization.DateFormat({pattern: 'MMMM'});

  var dataGroup = google.visualization.data.group(
    data,

    // group by column
    [{
      column: 0,
      label: 'Month',
      modifier: function (val) {
        return formatDate.formatValue(val);
      },
      type: 'string'
    }],

    // agg columns
    [{
      aggregation: google.visualization.data.count,
      column: 1,
      label: 'Tag Count',
      type: 'number'
    }]
  );

  var view = new google.visualization.DataView(dataGroup);
  view.setRows([2, 1, 0]);

  var chart = new google.visualization.ColumnChart(document.getElementById('chart_div'));
  chart.draw(view);

  var table = new google.visualization.Table(document.getElementById('table_div'));
  table.draw(view);
}

<script src="https://www.gstatic.com/charts/loader.js"></script>
<div id="chart_div"></div>
<div id="table_div"></div>

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

function drawChart() {
  var data = google.visualization.arrayToDataTable([
    ['date', 'tag_id'],
    [new Date('2016-09-29 06:47:47'), '04:0f'],
    [new Date('2016-09-29 14:48:42'), '04:0f'],
    [new Date('2016-10-29 06:47:47'), '99:9n'],
    [new Date('2016-11-29 06:48:42'), '05:m8'],
  ]);

  var formatDate = new google.visualization.DateFormat({pattern: 'MMMM'});

  var dataGroup = google.visualization.data.group(
    data,

    // group by column
    [{
      column: 0,
      label: 'Month',
      modifier: function (val) {
        return formatDate.formatValue(val);
      },
      type: 'string'
    }],

    // agg columns
    [{
      aggregation: google.visualization.data.count,
      column: 1,
      label: 'Tag Count',
      type: 'number'
    }]
  );

  var view = new google.visualization.DataView(dataGroup);
  view.setRows([2, 1, 0]);

  var chart = new google.visualization.ChartWrapper({
    chartType: 'ColumnChart',
    containerId: 'chart_div',
    dataTable: view
  });
  chart.draw();

  var table = new google.visualization.ChartWrapper({
    chartType: 'Table',
    containerId: 'table_div',
    dataTable: view
  });
  table.draw();
}

<script src="https://www.gstatic.com/charts/loader.js"></script>
<div id="chart_div"></div>
<div id="table_div"></div>