Re: how do you write aggregate function

On Mon, Mar 10, 2008 at 10:01:47AM -0500, Justin wrote:
> i wish that could work but need to keep track of the individual weights
> as its a percentage of the total amount of the weight.

Unless you have a different meaning of weighted average to me, I don't
think you do. AFAIK this would produce exactly the same result as what
your code does:

state_function(state,weight,value)
state[0] = state[0]+weight
state[1] = state[1]+weight*value

final_function(state)
return state[1]/state[0]

The state[0] is the same as your _sumedWeight. Because it's a constant in
the second loop you can do the division after. state[1] is your
_sumedWxV times _sumedWeight.

Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> Please line up in a tree and maintain the heap invariant while
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