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RE: len() on mutables vs. immutables

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  RE: len() on mutables vs. immutables "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2012-10-18 20:26 +0000

#31683 — RE: len() on mutables vs. immutables

Ian Kelly wrote:
> Sent: Thursday, October 18, 2012 2:39 PM
> To: Python
> Subject: Re: len() on mutables vs. immutables
> 
> On Thu, Oct 18, 2012 at 1:18 PM, Prasad, Ramit
> <ramit.prasad@jpmorgan.com> wrote:
> > Why does pointer arithmetic work for dicts? I would think the position
> > of a value would be based on the hash of the key and thus "random" for
> > the context of this conversation.
> 
> It doesn't.  len() on CPython dicts is O(1) because the dict keeps
> track of how many items it contains.  It needs to do this anyway so
> that it can determine when to grow the internal hash table.

That is what I was thinking "should" happen. Thanks for the 
clarification Ian.


Ramit Prasad


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