Calculates the entropy of any old input range of observations more quickly
than entropy(), provided that all equal values are adjacent. If the input
is sorted by more than one key, i.e. structs, the result will be the joint
entropy of all of the keys. The compFun alias will be used to compare
adjacent elements and determine how many instances of each value exist.

Calculates the entropy of any old input range of observations more quickly than entropy(), provided that all equal values are adjacent. If the input is sorted by more than one key, i.e. structs, the result will be the joint entropy of all of the keys. The compFun alias will be used to compare adjacent elements and determine how many instances of each value exist.