[Oz] beginner: distributing data fields over documents

[Filip Konvicka]

Hi,

some ideas from the top of my head...one obvious way of doing this is 
using a Dictionary to keep track of occurrences of each number (i.e. 
scan the input list twice, first constructing the dictionary and next 
constructing the output list). Another (memory-friendly) is sorting the 
input list and doing a simple scan ((n*log n) + n). There are 
bucket-sort-inspired variations on this one that greatly reduce the 
complexity (that might even outperform the dictionary approach).

HTH,
Filip

> I have a list of n numbers than I want to partition into two 
> subsets--the first set contains numbers that only appear in the list one 
> time, the second set contains numbers that appear twice.
> For example, a list such as {1, 2, 3, 4, 2, 3} would be partitioned into 
> {1, 4} and {2,3}.
>  
> I could recurse through the list, picking off the first element each 
> time, and adding it to one list the first time it was encountered, and 
> then removing it from the first list and adding it to the second if it 
> is encountered a second time.
>  
> My question is this:
> Is there a more efficient way to partition this list in OZ--
> such as using the List partition function, or or one of the "drop..." 
> functions?
>  
> George Rudolph