title: Highcharts - Update a series point [x,y] values?
body: <p>I'm trying to update a point[x,y] in the chart.
  What's the problem? 
  Ok, I  chart and its chart series are like this:</p>
  
  <pre><code>     series: [
              {
                  enableMouseTracking: false,
                  name: 'Line1',
                  type: 'line',
                  color: '#5d5d5d',
                  yAxis: 1,
                  data: [[12000, 55.068493], [15064, 42.842]],
                  marker: {
                      symbol: 'circle'
                  }
              },
              {
                  enableMouseTracking: false,
                  name: 'Line2',
                  type: 'line',
                  color: '#5d5d5d',
                  yAxis: 1,
                  marker: {
                      symbol: 'circle'
                  },
                  data: [[12000, 57.671527], [16000, 42.620069]]
  
              },{
                  name: 'TOM',
                  //type: 'line',
                  color: '#ff4100',
                  yAxis: 1,
                  marker: {
                      symbol: 'url(icons/tom.png)'
                  },
                  data: [
                      {
                          id:'tom_point',
                          color: '#00FF00',
                          y: fi_variable,
                          x: tom_variable
                      }
                  ]
               }
  </code></pre>
  
  <p>Now the thing is that, I'm checking if <code>fi_variable</code> or <code>tom_variable</code> has changed and if its true, update these two variables, and finally update the chart.</p>
  
  <p>I have tried already, some  methods like  <code>chart.series[0].data[0].update(y = 10);</code> and its working for some points with fixed x,y values, but no luck for the rest of the points.
  For Instance I use <code>chart.series[0].data[1].update(y = 10);</code> will work ok,
  but this <code>chart.series[0].data[3].update(y = 10);</code> will not work.</p>
  
  <p>1- Is there any way to replace the <code>data[0]</code> from the above code line with an <code>id</code> of a point in our case <code>tom_point</code> ?</p>
  
  <p>Also I've tried this <code>chart.series[0].setData([[tom_variable,fi_variable, 'tom_point']]);</code>
  and again it wont working when the point is with an id or without fixed values.</p>
  
  <p>But If I try <code>chart.series[0]data[0].setData([[tom_variable,fi_variable]]);</code> it works but again not on 3rd element (in our case - as shown above) of the series.</p>
  
  <p>I can get the values for this point with the following, 
  <code>var tomPoint = chart.get('tom_point').y;</code>
  but I can't set any x,y values back to chart and update it (the chart).</p>
  
  <p>I have also tried to check if the variables have changed and to redraw the chart with chart.redraw but nothing.</p>
  
  <p>Any Ideas how can I get this to work?
  Am I losing something?</p>
  
  <p>Thank you in Advance for your time.</p>