Re^3: Removing elemets from an array

in reply to Re^2: Removing elemets from an array
in thread Removing elemets from an array

This is very interesting. But for the moment i don't have any idea why it is so.

Perhaps some of the involved brothers would like to comment/interprete the result so we can learn something new?

Best regards, Karl

ŤThe Crux of the Biscuit is the Apostropheť

Comment on Re^3: Removing elemets from an array
Re^4: Removing elemets from an array by Lotus1 (Hermit) on Dec 30, 2012 at 16:44 UTC
Thanks for setting up the benchmark in the first place, it has been fun seeing the performance of the different approaches. Nested loops don't scale well. When there were only 2 items for the outer loop it was really fast. I've seen folks here toss around the Big O notation and although I hadn't heard of it before Perlmonks I figured out they were talking about linear growth as opposed to exponential or some other function for the execution time related to the size of the data set. The nested loop approach seems to be O(n^2) but I'm still learning so hopefully someone will weigh in if I'm off base.	[reply]
Re^5: Removing elemets from an array by karlgoethebier (Friar) on Dec 31, 2012 at 18:02 UTC
Thank you and HNY. Best regards, Karl ŤThe Crux of the Biscuit is the Apostropheť	[reply]
Re^4: Removing elemets from an array (optimization) by LanX (Monsignor) on Dec 30, 2012 at 17:15 UTC
Every operation in Perl - like any abstraction - has an overhead which can't be compensated by its C-implementation. So tending to use as few as possible perl-commands which do mass-operations means to reduce overhead and delaying the task to highly optimized C. Loops (including maps) are just multiplying the amount of executed commands (just imagine the linearized alternative which is even faster as the loop...) so my approach is the fastest because its basically reduced to only 3 perl commandsš 1. setting a hash 2. deleting a slice from that hash 3. reading the resulting hash OTOH my approach has drawbacks, depending on the task, it's only suitable for real sets of strings. Arrays can contain repeated data or other datatypes like refs. EDIT: you might be interested in Using hashes for set operations... Cheers Rolf PS: of course there are still loops working under the hood, but they are already optimized in C.	[reply]
Re^5: Removing elemets from an array (optimization) by karlgoethebier (Friar) on Dec 31, 2012 at 18:00 UTC
ThanX - and especially for the link HNY and best regards, Karl ŤThe Crux of the Biscuit is the Apostropheť	[reply]


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Re^3: Removing elemets from an array

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