title: Flot javascript graphing: setData for multiple series
body: <p>I am trying to plot 6 time series at once, and update their values every few ms.</p>
  <p>Here is how I initially plot the data which works fine:</p>
  <pre><code>var d1 = [];
  var d2 = [];
  var d3 = [];
  var d4 = [];
  var d5 = [];
  var d6 = [];
  
  d1 = getRandomData(d1, totalPoints);
  d2 = getRandomData(d2, totalPoints);
  d3 = getRandomData(d3, totalPoints);
  d4 = getRandomData(d4, totalPoints);
  d5 = getRandomData(d5, totalPoints);
  d6 = getRandomData(d6, totalPoints);
  
  var plot = $.plot(&quot;#placeholder&quot;, [{
  data: d1,
  lines: { show: true, fill: false }
  }, {
  data: d2,
  lines: { show: true, fill: false }
  }, {
  data: d3,
  lines: { show: true, fill: false }
  }, {
  data: d4,
  lines: { show: true, fill: false }
  }, {
  data: d5,
  lines: { show: true, fill: false }
  }, {
  data: d6,
  lines: { show: true, fill: false }
  }]);
  </code></pre>
  <p>But my update function doesn't work:</p>
  <pre><code>function update() {
  
  d1 = getRandomData(d1, totalPoints);
  d2 = getRandomData(d2, totalPoints);
  d3 = getRandomData(d3, totalPoints);
  d4 = getRandomData(d4, totalPoints);
  d5 = getRandomData(d5, totalPoints);
  d6 = getRandomData(d6, totalPoints);
  
  plot.setData([d1, d2, d3, d4, d5, d6]);
  
  // Since the axes don't change, we don't need to call plot.setupGrid()
  plot.draw();
  setTimeout(update, updateInterval);
  
  }
  //update();
  </code></pre>
  <p>When I uncomment and call <code>update()</code>, the graph goes blank. But I know data is being loaded fine initially without calling it.</p>
  <p>How can I update my d arrays and redraw the graph properly?</p>