title: Scatter plot with colored markers + colormap in ECharts
body: <p>After reading the ECharts documentation and looking at examples, I haven't found anything that would allow coloring scatter plot markers automatically according to a continuous data dimension.</p>
  
  <p>Basically, I'm trying to plot something like this: </p>
  
  <p><a href="https://i.stack.imgur.com/QIaHC.png" rel="noreferrer"><img src="https://i.stack.imgur.com/QIaHC.png" alt="enter image description here"></a></p>
  
  <p>What would be the right approach to that problem in ECharts?</p>
  
  <hr>
  
  <p>For example modifying the <a href="https://echarts.apache.org/examples/en/editor.html?c=scatter-simple" rel="noreferrer">basic scatter plot example</a> to use a scalar <code>color</code> for all data points is possible as follows:</p>
  
  <pre class="lang-js prettyprint-override"><code>option = {
      xAxis: {},
      yAxis: {},
      series: [{
          symbolSize: 20,
          data: [
              [10.0, 8.04],
              [8.0, 6.95],
              [13.0, 7.58],
              [9.0, 8.81],
              [11.0, 8.33],
              [14.0, 9.96],
              [6.0, 7.24],
              [4.0, 4.26],
              [12.0, 10.84],
              [7.0, 4.82],
              [5.0, 5.68]
          ],
          color: '#F00',
          type: 'scatter'
      }]
  };
  </code></pre>
  
  <p>What I would like to achieve is to pass in a data vector like this for the <code>color</code>, which doesn't work:</p>
  
  <pre class="lang-js prettyprint-override"><code>option = {
      xAxis: {},
      yAxis: {},
      series: [{
          symbolSize: 20,
          data: [
              [10.0, 8.04],
              [8.0, 6.95],
              [13.0, 7.58],
              [9.0, 8.81],
              [11.0, 8.33],
              [14.0, 9.96],
              [6.0, 7.24],
              [4.0, 4.26],
              [12.0, 10.84],
              [7.0, 4.82],
              [5.0, 5.68]
          ],
          color: [
              0.11,
              0.53,
              0.76,
              0.01,
              0.53,
              0.19,
              0.64,
              0.65,
              0.34,
              0.23,
              0.81
          ],
          type: 'scatter'
      }]
  };
  </code></pre>
  
  <p>The only solution I see is:</p>
  
  <ul>
  <li>computing the colors from the data manually,</li>
  <li>using sequences of only length 1 to have control over the color of each scatter point.</li>
  </ul>
  
  <p>Is there a mechanism in ECharts that simplifies this process?</p>