title: Highcharts x axis categories
body: <p>Could you help me? I created this heatmap chart.. and I see at the x axis a "7" number. Maybe I'm tired.. but what is the problem? (I didn't see similar before this)</p>
  
  <p>Many thanks!</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>$(document).ready(function() {  
     var chart = {      
        type: 'heatmap',
        marginTop: 40,
        marginBottom: 80
     };
     var title = {
        text: 'Sales per employee per weekday'   
     };     
  
     var xAxis = {
        categories: ['Monday','Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday', 'Sunday']
     };
     
     var yAxis = {
        categories: ['1','2','3','4','5','6','7','8','9','10','11','12','13','14','15','16','17','18','19','20','21','22','23','24'],
        title: null
     };
     
     var colorAxis = {
        min: 0,
        minColor: '#FFFFFF',
        maxColor: Highcharts.getOptions().colors[0]
     };
  
     var legend = {
        align: 'right',
        layout: 'vertical',
        margin: 0,
        verticalAlign: 'top',
        y: 25,
        symbolHeight: 280
     };
  
     var tooltip = {
        formatter: function () {
           return '&lt;b&gt;' + this.series.xAxis.categories[this.point.x] + '&lt;/b&gt; sold &lt;br&gt;&lt;b&gt;' +
           this.point.value + '&lt;/b&gt; items on &lt;br&gt;&lt;b&gt;' + this.series.yAxis.categories[this.point.y] + '&lt;/b&gt;';
        }
     };
  
     var series= [{
        name: 'Sales per employee',
        borderWidth: 1,
        data: [[1,0,1],[1,1,1],[1,2,1],[1,3,1],[1,4,1],[1,5,1],[1,6,1],[1,7,1],[1,8,1],[1,9,1],[1,10,1],[1,11,1],[1,12,1],[1,13,1],[1,14,1],[1,15,1],[1,16,1],[1,17,1],[1,18,1],[1,19,1],[1,20,1],[1,21,1],[1,22,1],[2,0,1],[2,1,1],[2,2,1],[2,3,1],[2,4,1],[2,5,1],[2,6,1],[2,7,1],[2,8,1],[2,9,1],[2,10,1],[2,11,1],[2,12,1],[2,13,1],[2,14,1],[2,15,1],[2,16,1],[2,17,11],[2,18,1],[2,19,1],[2,20,1],[2,21,1],[2,22,1],[3,0,1],[3,1,1],[3,2,1],[3,3,1],[3,4,1],[3,5,1],[3,6,1],[3,7,1],[3,8,1],[3,9,1],[3,10,1],[3,11,1],[3,12,1],[3,13,1],[3,14,1],[3,15,1],[3,16,1],[3,17,1],[3,18,1],[3,19,1],[3,20,1],[3,21,1],[3,22,1],[4,0,1],[4,1,1],[4,2,1],[4,3,1],[4,4,1],[4,5,1],[4,6,1],[4,7,1],[4,8,1],[4,9,1],[4,10,21],[4,11,1],[4,12,15],[4,13,1],[4,14,1],[4,15,1],[4,16,1],[4,17,1],[4,18,1],[4,19,1],[4,20,1],[4,21,1],[4,22,1],[5,0,1],[5,1,1],[5,2,1],[5,3,1],[5,4,1],[5,5,1],[5,6,1],[5,7,1],[5,8,1],[5,9,1],[5,10,31],[5,11,1],[5,12,1],[5,13,1],[5,14,1],[5,15,1],[5,16,1],[5,17,1],[5,18,1],[5,19,1],[5,20,1],[5,21,1],[5,22,1],[6,0,1],[6,1,1],[6,2,1],[6,3,1],[6,4,1],[6,5,1],[6,6,1],[6,7,1],[6,8,1],[6,9,1],[6,10,1],[6,11,1],[6,12,1],[6,13,1],[6,14,1],[6,15,1],[6,16,1],[6,17,1],[6,18,1],[6,19,1],[6,20,1],[6,21,1],[6,22,1],[7,0,1],[7,1,1],[7,2,1],[7,3,1],[7,4,1],[7,5,1],[7,6,1],[7,7,1],[7,8,1],[7,9,1],[7,10,1],[7,11,1],[7,12,1],[7,13,1],[7,14,1],[7,15,1],[7,16,1],[7,17,1],[7,18,1],[7,19,1],[7,20,1],[7,21,1],[7,22,1]],
        dataLabels: {
           enabled: true,
           color: '#000000'
        }
     }];     
        
     var json = {};   
     json.chart = chart; 
     json.title = title;       
     json.xAxis = xAxis; 
     json.yAxis = yAxis; 
     json.colorAxis = colorAxis; 
     json.legend = legend; 
     json.tooltip = tooltip; 
     json.series = series;       
     
     $('#container').highcharts(json);
  });</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>   &lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"&gt;&lt;/script&gt;
     &lt;script src="https://code.highcharts.com/highcharts.js"&gt;&lt;/script&gt;    
     &lt;script src="https://code.highcharts.com/highcharts-more.js"&gt;&lt;/script&gt;    
     &lt;script src="https://code.highcharts.com/modules/heatmap.js"&gt;&lt;/script&gt; 
  &lt;div id="container" style="width: 550px; height: 500px; margin: 0 auto"&gt;&lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>Could you help me? I created this heatmap chart.. and I see drop to the x axis a "7" number. Maybe I'm tired.. but what is the problem? (I didn't see similar before this)</p>
  
  <p>Many thanks!</p>