push_element/2 - efficient sliding window

Ulf Wiger (AL/EAB) <>
Wed Aug 10 16:49:38 CEST 2005


Hmmm, I think I'll let someone else take care of that one. (:

I think tuples of 1,000,000 items are a bit ... impractical in
Erlang today.

/Uffe

> -----Original Message-----
> From: 
> [mailto:]On Behalf Of Joel Reymont
> Sent: den 10 augusti 2005 16:46
> To: Erlang Users' List
> Subject: Re: push_element/2 - efficient sliding window
> 
> 
> Go Uffe!
> 
> Now I just need another BIF to slide a tuple of a fixed size over a  
> large tuple. Then I would be happy :-). Say you have a tuple of  
> 1,000,000 items and I want to move a window of 100 items through it,  
> shifting it from 1 to 100 then from 2 to 101 and so on.
> 
> For extra credit it should not copy data but return a "reference"  
> which would indeed make it a "window".
> 
>      Joel
> 
> On Aug 10, 2005, at 4:23 PM, Ulf Wiger (AL/EAB) wrote:
> 
> > erlang:push_element(Tuple, Value) pushes value into position 1 of  
> > Tuple, shifting the existing values one step to the right. 
> This can  
> > be used as a fixed-size sliding window which costs the same as  
> > setelement/3 to update.
> 
> --
> http://wagerlabs.com/uptick
> 
> 
> 
> 



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