Re: suggestion for Averager

[Ken Cline]

On Wed, 7 Jul 1999, Marcus G. Daniels wrote:

> >>>>> "RLR" == Rick Riolo <address@hidden> writes:
> 
> RLR> (or is there a way to do this with existing tools?)
> 
> Not unless you pre-filter (and thus fix) the feed collection.
> Otherwise, there isn't; the denominator is always incremented.
> 
> Two solutions occur to me:
> 
>   1) Have Averager & Entropy accept two kinds of methods.  The first
>      form would be a method of N arguments that returns a double.  The
>      second form would be as a method of N + 1 arguments returning a
>      boolean where the extra argument is a pointer to the returned
>      double.
> 
>      + fast (no extra method invocations)
>      * "-(BOOL)value: (double *)val index: i" methods would be needed
>        to select among variables.
>    
>   2) Modify MessageProbe so that the called selector could be switched.
>      Averager, being a MessageProbe, could then internally temporarily
>      switch to the selection probe and back within the same computation.
> 
>      + no method calling convention to know about
>      - slower, a selection method must be called and then a query method
> 

How about a dynamically filtered collection?  You could
create the "FilteredCollection" with an existing collection
and a selector (e.g. M(isGreen)) and the resulting wrapper
object would skip over members of the internal collection.
That probably means you'd need a "FilteredIndex" to
complement the collection object.

Hmmm... It looks like the other solutions would definitely
be easier to implement.


_________________________________________________________
Ken Cline                             address@hidden
SAIC                                 VOICE (410) 571-0413
Annapolis, MD                          FAX (301) 261-8427






                  ==================================
   Swarm-Support is for discussion of the technical details of the day
   to day usage of Swarm.  For list administration needs (esp.
   [un]subscribing), please send a message to <address@hidden>
   with "help" in the body of the message.