On Tue, Dec 1, 2015 at 4:45 PM, Sven Van Caekenberghe <sven@stfx.eu> wrote:
> I am all for a cleanup, the current situation is confusing.
> The basic #sum should be fast AND work for empty collections with 0 as starting element.

> I know why the #anyOne is used, and that use case should be preserved, but it is less common IMHO.

I'm curious to be learn why?
cheers -ben

>
>> On 01 Dec 2015, at 09:38, Thierry Goubier <thierry.goubier@gmail.com> wrote:
>>
>> Hi Max,
>>
>> Interesting results...
>>
>> replacing the #yourself in newSum: cuts the runtime by a factor of two.
>> using an [:x | x ] block cost 10% compared to a direct version of sum.
>>
>> So the fastest sum is:
>>
>> sum
>>�� �� �� ��^ self
>>�� �� �� �� �� �� �� ��inject:
>>�� �� �� �� �� �� �� �� �� �� �� ��(self ifEmpty: [ ^ 0 ] ifNotEmpty: [ self anyOne ])
>>�� �� �� �� �� �� �� ��into: [ :sum :each | sum + each ]
>>
>> And
>>
>> sum
>>�� �� ��^ self sum: [:x | x ]
>>
>> is 10% slower.
>>
>> And
>>
>> sum
>>�� �� ��^ self sum: #yourself
>>
>> is 100% slower (i.e. x2)
>>
>> It may be wise to avoid using #yourself for a block.
>>
>> Thierry
>>
>>
>> 2015-12-01 9:17 GMT+01:00 Max Leske <maxleske@gmail.com>:
>> Hi guys,
>>
>> Collection defines #sum:, #detectSum: and #sumNumbers:, all of which accomplish the same (in principal) but with subtle differences:
>>
>> #sum:
>> - uses #inject:into: with #anyOne as the injected element and will thus fail for empty collections
>>
>> #detectSum:
>> - uses ���nextValue + sum��� instead of ���sum + nextValue��� which makes it a lot slower when dealing with large numbers (primitive fails and number conversion is necessary)
>>
>> #sumNumbers:
>> - same as #sum but doesn���t fail for empty collections. Only good for numbers though.
>>
>>
>> Benchmarks:
>>
>> [ 100 timesRepeat: [ (1 to: 1000000) sum: #yourself ] ] timeToRun 18062
>> [ 100 timesRepeat: [ (1 to: 1000000) detectSum: #yourself ] ] timeToRun 42391
>> [ 100 timesRepeat: [ (1 to: 1000000) sumNumbers: #yourself ] ] timeToRun 18096
>>
>>
>>
>> Can we settle for a single implementation? Such as (modified from #sumNumbers:):
>>
>> newSum: aBlock
>>�� �� �� �� ��^ self
>>�� �� �� �� �� �� �� �� ��inject: (self
>>�� �� �� �� �� �� �� �� �� �� �� �� ��ifEmpty: [ 0 ]
>>�� �� �� �� �� �� �� �� �� �� �� �� ��ifNotEmpty: [ self anyOne ])
>>�� �� �� �� �� �� �� �� ��into: [ :sum :each |�� sum + (aBlock value: each) ]
>>
>> This implementation combines the best of the three implementations I think. Benchmark:
>>
>> [ 100 timesRepeat: [ (1 to: 1000000) newSum: #yourself ] ] timeToRun 17955
>>
>>
>> BTW, there is also the message #sum, which suffers from the same problem as #sum: (the implementation is basically a copy). #sum could be implemented as
>>
>> sum
>>�� �� �� �� ��^ self sum: [ :x | x ]
>>
>>
>> As for the name for the new method, I suggest #sum:.
>>
>> Cheers,
>> Max
>>
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