Speed revisited

Andrea Griffini agriff at tin.it
Sun Jan 9 23:51:47 CET 2005


On 9 Jan 2005 12:39:32 -0800, "John Machin" <sjmachin at lexicon.net>
wrote:

>Tip 1: Once you have data in memory, don't move it, move a pointer or
>index over the parts you are inspecting.
>
>Tip 2: Develop an abhorrence of deleting data.

I've to admit that I also found strange that deleting the
first element from a list is not O(1) in python. My wild
guess was that the extra addition and normalization required
to have insertion in amortized O(1) and deletion in O(1) at
both ends of a random access sequence was going to have
basically a negligible cost for normal access (given the
overhead that is already present in python).

But I'm sure this idea is too obvious for not having been
proposed, and so there must reasons for refusing it
(may be the cost to pay for random access once measured was
found being far from negligible, or that the extra memory
overhead per list - one int for remembering where the live
data starts - was also going to be a problem).

Andrea



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