title: Plotly.js pie chart values format
body: <p>I'm creating some pie charts with Plotly.js but I can't figure out how to set the value format. If my number is 19.231, I get 19.2. I want 19.2310, with 4 digit precision. My data and layout follow here:</p>
  
  <pre><code>var data = [{
      values: values,
      labels: labels,
      type: 'pie',
      marker: {
          colors: colors
      },
      textfont: {
          family: 'Helvetica, sans-serif',
          size: 48,
          color: '#000'
      }
  }];
  var layout = {
      height: 1350,
      width: 1500,
      title: title,
      titlefont: {
          family: 'Helvetica, sans-serif',
          size: 58,
          color: '#000'
      },
      legend: {
          x: 1.1,
          y: 0.5,
          size: 40,
          font: {
              family: 'Helvetica, sans-serif',
              size: 48,
              color: '#000'
          }
      }
  };
  </code></pre>