I'm using ExtJS 4 to draw a very simple line chart. This is a simplified snippet from my code:

Code:
 

    Ext.create('Ext.Panel', {
            width:  '100%',
            height: 300,
            hidden: false,
            renderTo: Ext.Element.get('container'),
            layout: 'fit',
            items: {
                xtype: 'chart',
                animate: false,
                store: plots[title]['instances'][instance]['store'],
                axes: [{
                    type: 'Numeric',
                    position: 'left',
                    fields: ['samples'],
                    minimum : minimum,
                    maximum : maximum,
                    grid : true,
                    title: plots[title]['yLabel']
                }, {
                    type: 'Category',
                    position: 'bottom',
                    fields: ['time'],
                    title: plots[title]['xLabel']
                }],
                series: [{
                    type: 'line',
                    highlight: {
                        size: 7,
                        radius: 7
                    },
                    axis: 'left',
                    xField: 'time',
                    yField: 'samples',
                    showMarkers: false,
                    style: {
                        fill: '#18428E',
                        stroke: '#18428E',
                        'stroke-width': 3
                    },
                }]
            }
        });
The problem is that time series on the x axis is very long as a result the label tend to overlap. In ExtJs this was not happening because only a subset of the label was actually visualized. Is there a way to implement this kind of grouping/sampling also in js4.

The data on the x-axis is a data obtained from a unix timestamp.\

Thanks
R.