    /**
     * @class Ext.chart.axis.Category
     *
     * A type of axis that displays items in categories. This axis is generally used to
     * display categorical information like names of items, month names, quarters, etc.
     * but no quantitative values. For that other type of information `Number`
     * axis are more suitable.
     *
     * As with other axis you can set the position of the axis and its title. For example:
     *
     *     @example
     *     var store = Ext.create('Ext.data.JsonStore', {
     *         fields: ['name', 'data1', 'data2', 'data3', 'data4', 'data5'],
     *         data: [
     *             {'name':'metric one', 'data1':10, 'data2':12, 'data3':14, 'data4':8, 'data5':13},
     *             {'name':'metric two', 'data1':7, 'data2':8, 'data3':16, 'data4':10, 'data5':3},
     *             {'name':'metric three', 'data1':5, 'data2':2, 'data3':14, 'data4':12, 'data5':7},
     *             {'name':'metric four', 'data1':2, 'data2':14, 'data3':6, 'data4':1, 'data5':23},
     *             {'name':'metric five', 'data1':27, 'data2':38, 'data3':36, 'data4':13, 'data5':33}
     *         ]
     *     });
     *
     *     Ext.create('Ext.chart.Chart', {
     *         renderTo: Ext.getBody(),
     *         width: 500,
     *         height: 300,
     *         store: store,
     *         axes: [{
     *             type: 'Numeric',
     *             position: 'left',
     *             fields: ['data1', 'data2', 'data3', 'data4', 'data5'],
     *             title: 'Sample Values',
     *             grid: {
     *                 odd: {
     *                     opacity: 1,
     *                     fill: '#ddd',
     *                     stroke: '#bbb',
     *                     'stroke-width': 1
     *                 }
     *             },
     *             minimum: 0,
     *             adjustMinimumByMajorUnit: 0
     *         }, {
     *             type: 'Category',
     *             position: 'bottom',
     *             fields: ['name'],
     *             title: 'Sample Metrics',
     *             grid: true,
     *             label: {
     *                 rotate: {
     *                     degrees: 315
     *                 }
     *             }
     *         }],
     *         series: [{
     *             type: 'area',
     *             highlight: false,
     *             axis: 'left',
     *             xField: 'name',
     *             yField: ['data1', 'data2', 'data3', 'data4', 'data5'],
     *             style: {
     *                 opacity: 0.93
     *             }
     *         }]
     *     });
     *
     * In this example with set the category axis to the bottom of the surface, bound the axis to
     * the `name` property and set as title _Month of the Year_.
     */
    Ext.define('Ext.chart.axis.Category', {

        /* Begin Definitions */

        extend: 'Ext.chart.axis.Axis',

        alternateClassName: 'Ext.chart.CategoryAxis',

        alias: 'axis.category',

        // @private
        isCategoryAxis: true,

        /* End Definitions */

        // @private constrains to datapoints between minimum and maximum only
        doConstrain: function() {
            var me = this,
                chart = me.chart,
                store = chart.getChartStore(),
                items = store.data.items,
                series = chart.series.items,
                seriesLength = series.length,
                data = [], i

            for (i = 0; i < seriesLength; i++) {
                if (series[i].type === 'bar' && series[i].stacked) {
                    // Do not constrain stacked bar chart.
                    return;
                }
            }

            for (i = me.minimum; i < me.maximum; i++) {
                data.push(items[i]);
            }

            chart.setSubStore(new Ext.data.Store({
                model: store.model,
                data: data
            }));
        },

        // @private creates an array of labels to be used when rendering.
        setLabels: function() {
            var store = this.chart.getChartStore(),
                data = store.data.items,
                d, dLen, record,
                fields = this.fields,
                ln = fields.length,
                labels,
                name,
                i;

            labels = this.labels = [];
            for (d = 0, dLen = data.length; d < dLen; d++) {
                record = data[d];
                for (i = 0; i < ln; i++) {
                    name = record.get(fields[i]);
                    //<debug>
                    if (Ext.Array.indexOf(labels, name) > -1) {
                        Ext.log.warn('Duplicate category in axis, ' + name);
                    }
                    //</debug>
                    labels.push(name);
                }
            }
        },

        // @private calculates labels positions and marker positions for rendering.
        applyData: function() {
            this.callParent();
            this.setLabels();
            var count = this.chart.getChartStore().getCount();
            return {
                from: 0,
                to: count - 1,
                power: 1,
                step: 1,
                steps: count - 1
            };
        }
    });