pie.sort()

pie.sort([compare])

If compare is specified, sets the data comparator to the specified function and returns this pie generator. If compare is not specified, returns the current data comparator, which defaults to null. If both the data comparator and the value comparator are null, then arcs are positioned in the original input order. Otherwise, the data is sorted according to the data comparator, and the resulting order is used. Setting the data comparator implicitly sets the value comparator to null.

The compare function takes two arguments a and b, each elements from the input data array. If the arc for a should be before the arc for b, then the comparator must return a number less than zero; if the arc for a should be after the arc for b, then the comparator must return a number greater than zero; returning zero means that the relative order of a and b is unspecified. For example, to sort arcs by their associated name:

pie.sort(function(a, b) { return a.name.localeCompare(b.name); });

Sorting does not affect the order of the generated arc array which is always in the same order as the input data array; it merely affects the computed angles of each arc. The first arc starts at the start angle and the last arc ends at the end angle.