* @param groupingComparator produces the groups in the pie chart
* @param keyFunction produces the keys of the groups in the pie chart
* @param valueFunction produces the values of the groups in the pie chart
*/
public EventListPieDataset(EventList<E> source, Comparator<E> groupingComparator, FunctionList.Function<List<E>, Comparable<K>> keyFunction, FunctionList.Function<List<E>, Number> valueFunction) {
this.groupingList = new GroupingList(source, groupingComparator);
this.sourceList = this.groupingList;
this.keyList = new FunctionList(this.groupingList, keyFunction);
this.valueList = new FunctionList(this.groupingList, valueFunction);
this.groupingList.addListEventListener(this.datasetEventListener);