add legendLabelAccessor to piechart

dc.js

@@ -681,6 +681,7 @@ dc.baseMixin = function (_chart) {
     var _keyAccessor = dc.pluck('key');
     var _valueAccessor = dc.pluck('value');
     var _label = dc.pluck('key');
+    var _legendLabelAccessor = dc.pluck('key');
 
     var _ordering = dc.pluck('key');
     var _orderSort;
@@ -1544,6 +1545,27 @@ dc.baseMixin = function (_chart) {
         return _chart;
     };
 
+
+    /**
+    #### .legendLabelAccessor([legendLabelAccessorFunction])
+    Set or get the legend label accessor function. The legend label accessor function is used to retrieve the
+    value from the legend label for the crossfilter group.
+    ```js
+    // default legenLabel accessor
+    chart.legendLabelAccessor(function(d) { return d.key; });
+    // custom legen label accessor for a multi-value crossfilter reduction
+    chart.legendLabelAccessor(function(p) { return "Custom Legend:" + p.key; });
+    ```
+
+    **/
+    _chart.legendLabelAccessor = function (_) {
+        if (!arguments.length) {
+            return _legendLabelAccessor;
+        }
+        _legendLabelAccessor = _;
+        return _chart;
+    };
+
     /**
     #### .label([labelFunction])
     Set or get the label function. The chart class will use this function to render labels for each
@@ -3746,6 +3768,7 @@ dc.pieChart = function (parent, chartGroup) {
     var _chart = dc.capMixin(dc.colorMixin(dc.baseMixin({})));
 
     _chart.colorAccessor(_chart.cappedKeyAccessor);
+    _chart.legendLabelAccessor(_chart.cappedKeyAccessor);
 
     _chart.title(function (d) {
         return _chart.cappedKeyAccessor(d) + ': ' + _chart.cappedValueAccessor(d);
@@ -4123,7 +4146,7 @@ dc.pieChart = function (parent, chartGroup) {
 
     _chart.legendables = function () {
         return _chart.data().map(function (d, i) {
-            var legendable = {name: d.key, data: d.value, others: d.others, chart:_chart};
+            var legendable = {name: _chart.legendLabelAccessor().call(this, d, i), data: d.value, others: d.others, chart:_chart};
             legendable.color = _chart.getColor(d, i);
             return legendable;
         });

spec/pie-chart-spec.js

@@ -658,6 +658,32 @@ describe('dc.pieChart', function() {
             valueDimension.filterAll();
         });
     });
+
+
+    describe('legends with label', function() {
+        var chart;
+        beforeEach(function() {
+            chart = buildChart("pie-chart-legend")
+                .cap(3)
+                .legend(dc.legend())
+                .legendLabelAccessor(function(d){
+                   return d.key + " labeled";
+                })
+                .render();
+        });
+        it('should generate items for each slice', function() {
+            expect(chart.selectAll('g.dc-legend g.dc-legend-item').size()).toEqual(chart.data().length);
+        });
+        it('should include "others" item labeled', function() {
+            var numOthersGroups = chart.selectAll('g.dc-legend g.dc-legend-item text').filter(function(d, i) {
+                return d.name == "Others labeled";
+            }).size();
+            expect(numOthersGroups).toEqual(1);
+        });
+        afterEach(function() {
+            valueDimension.filterAll();
+        });
+    });
 });
 
 

src/base-mixin.js

@@ -31,6 +31,7 @@ dc.baseMixin = function (_chart) {
     var _keyAccessor = dc.pluck('key');
     var _valueAccessor = dc.pluck('value');
     var _label = dc.pluck('key');
+    var _legendLabelAccessor = dc.pluck('key');
 
     var _ordering = dc.pluck('key');
     var _orderSort;
@@ -894,6 +895,27 @@ dc.baseMixin = function (_chart) {
         return _chart;
     };
 
+
+    /**
+    #### .legendLabelAccessor([legendLabelAccessorFunction])
+    Set or get the legend label accessor function. The legend label accessor function is used to retrieve the
+    value from the legend label for the crossfilter group.
+    ```js
+    // default legenLabel accessor
+    chart.legendLabelAccessor(function(d) { return d.key; });
+    // custom legen label accessor for a multi-value crossfilter reduction
+    chart.legendLabelAccessor(function(p) { return "Custom Legend:" + p.key; });
+    ```
+
+    **/
+    _chart.legendLabelAccessor = function (_) {
+        if (!arguments.length) {
+            return _legendLabelAccessor;
+        }
+        _legendLabelAccessor = _;
+        return _chart;
+    };
+
     /**
     #### .label([labelFunction])
     Set or get the label function. The chart class will use this function to render labels for each

src/pie-chart.js

@@ -51,6 +51,7 @@ dc.pieChart = function (parent, chartGroup) {
     var _chart = dc.capMixin(dc.colorMixin(dc.baseMixin({})));
 
     _chart.colorAccessor(_chart.cappedKeyAccessor);
+    _chart.legendLabelAccessor(_chart.cappedKeyAccessor);
 
     _chart.title(function (d) {
         return _chart.cappedKeyAccessor(d) + ': ' + _chart.cappedValueAccessor(d);
@@ -428,7 +429,8 @@ dc.pieChart = function (parent, chartGroup) {
 
     _chart.legendables = function () {
         return _chart.data().map(function (d, i) {
-            var legendable = {name: d.key, data: d.value, others: d.others, chart:_chart};
+            var legendable = {  name: _chart.legendLabelAccessor().call(this, d, i),
+                                data: d.value, others: d.others, chart:_chart };
             legendable.color = _chart.getColor(d, i);
             return legendable;
         });