pie.sortValues()

pie.sortValues([compare])

If compare is specified, sets the value comparator to the specified function and returns this pie generator. If compare is not specified, returns the current value comparator, which defaults to descending value. The default value comparator is implemented as:

function compare(a, b) {
  return b - a;
}

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 value comparator implicitly sets the data comparator to null.

The value comparator is similar to the data comparator, except the two arguments a and b are values derived from the input data array using the value accessor, not the data elements. 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 ascending value:

pie.sortValues(function(a, b) { return a - b; });

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.