unique_mapping - partition an array into groups

mapping unique_mapping(array arr, string fun, object ob, ...);

mapping unique_mapping(array arr, function f, ...);

unique_mapping() evaluates the function 'f' with each element of the
array 'arr', and constructs a mapping with the return values as keys,
and subarrays of elements that returned value value as values.

See also:
 unique_array

 Tim Hollebeek  Beek@ZorkMUD, Lima Bean, IdeaExchange, and elsewhere
