data.addRows无法在谷歌图表中工作

Question

我正在尝试使用谷歌API绘制折线图.

但是没有绘制图表,我可以在data.addRows(rows)中识别出一些错误; 因为此data.addRows行之后的警报不会弹出.

如果我在data.addRows(行)之前提供警报弹出窗口.

我不知道这里出了什么问题.任何帮助深表感谢.

<script type="text/javascript">
      google.load('visualization', '1.0', {'packages':['corechart']});

      function drawLineChart() {
          var date = 0;
          var status = 0;
          var rows = new Array();
          var data = new google.visualization.DataTable();
          var $attendance_date =  new Array();
          var $attendance_status = new Array();

          $attendance_date[0] = '2004';
          $attendance_date[1] = '2005';
          $attendance_date[2] = '2006';

          $attendance_status[0] = 1;
          $attendance_status[1] = 3;
          $attendance_status[2] = 5;

          rows.push(['Year', 'Sales']); 
          for(var i = 0; i < 3 ; i++) {
            date = $attendance_date[i];
            status = parseInt($attendance_status[i]);
            rows.push([date, status]);
          }

          data.addColumn('string', 'Subject');
          //  alert(rows);
          data.addRows(rows);
          alert(rows);

          var options = {
          title: 'My Chart',
          'width':900,
           'height':320, 
           'backgroundColor': '#d9d9e4'
          };

          var chart = new google.visualization.LineChart(document.getElementById('chart_attendance_div'));
          chart.draw(data, options);
      }
</script>

Answer 1

你正在做的事情有很多问题,让我们一个接一个地看看.

首先,当使用addRow和时,使用命令addColumn定义标题addColumn.所以你可以删除以下行:

rows.push(['Year', 'Sales']); 

其次,当您确实有两列('Year'和'Sales')时,您将单个列定义为'Subject'.您应该定义两列:

data.addColumn('string', 'Year');
data.addColumn('number', 'Sales');

完成此操作后,您可以将addRows命令与最终(工作)代码一起使用:

function drawVisualization() {
  var date = 0;
  var status = 0;
  var rows = new Array();
  var data = new google.visualization.DataTable();
  var $attendance_date =  new Array();
  var $attendance_status = new Array();

  $attendance_date[0] = '2004';
  $attendance_date[1] = '2005';
  $attendance_date[2] = '2006';

  $attendance_status[0] = 1;
  $attendance_status[1] = 3;
  $attendance_status[2] = 5;

  // This line is commented out because it should be deleted
  // rows.push(['Year', 'Sales']);
  for(var i = 0; i < 3 ; i++) {
    date = $attendance_date[i];
    status = parseInt($attendance_status[i]);
    rows.push([date, status]);
  }
  // This line is commented out because it should be deleted
  // data.addColumn('string', 'Subject');

  // These lines should be added for column headers
  data.addColumn('string', 'Year');
  data.addColumn('number', 'Sales');

  //  alert(rows); 
  data.addRows(rows);
  // alert(rows);

  var options = {
    title: 'My Chart',
    'width':900,
    'height':320,
    'backgroundColor': '#d9d9e4'
  };

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

但是,如果你要走这么远,你可以继续下一步.现在,您正在创建一个新数组,在for循环中填充它,并将数组传递给addRows命令.为什么不切断中间人呢？

      var data = new google.visualization.DataTable();
      var $attendance_date =  new Array();
      var $attendance_status = new Array();

      $attendance_date[0] = '2004';
      $attendance_date[1] = '2005';
      $attendance_date[2] = '2006';

      $attendance_status[0] = 1;
      $attendance_status[1] = 3;
      $attendance_status[2] = 5;

      data.addColumn('string', 'Year');
      data.addColumn('number', 'Sales');

      for(var i = 0; i < 3 ; i++) {
        data.addRow([$attendance_date[i], parseInt($attendance_status[i])])
      }

Presto,你的代码更简单,你正在跳过一步.