P.S., Hah I should have called it unique-by, it's too early in the morning!
P.P.S., I committed this word into sets.extras, with one small change
besides the name which is to size the hash-set capacity by the length of
the sequence.
On Fri, Nov 18, 2016 at 6:54 AM, John Benediktsson <mrj...@gmail.com> wrote:
> Maybe something like this:
>
> : duplicates-by ( seq quot: ( elt -- key ) -- seq' )
> HS{ } clone '[ @ _ ?adjoin ] filter ; inline
>
> Then you can use it:
>
> IN: scratchpad { 1 2 3 4 5 } [ 2/ ] duplicates-by
> { 1 2 4 }
>
> IN: scratchpad sequence-of-tuples [ hash>> ] duplicates-by
>
> It would keep the first element that matches by key and drop all the
> subsequent ones.
>
>
>
> On Fri, Nov 18, 2016 at 6:36 AM, Alexander Ilin <ajs...@yandex.ru> wrote:
>
>> Hello, all!
>>
>> I have an interesting little task for you today.
>>
>> Let's say you have a sequence of tuples, and you want to remove all
>> tuples with duplicate ids, so that in the new sequence there is only one
>> tuple with each id.
>>
>> Here's my solution:
>>
>> TYPED: dedupe-by-hash ( seq: sequence -- seq: sequence )
>> dup [ hash>> ] map >hash-set [
>> [ hash>> ] dip
>> [ in? ] [ delete ] 2bi
>> ] curry filter ;
>>
>> This is not the first time I'm solving this task, and I begun to wonder
>> - is there something similar in the Factor library?
>>
>> Is this the simplest/most efficient implementation?
>>
>> Is it possible to generalize it to work for any slot like so:
>>
>> TYPED: dedupe-by-slot ( seq slot -- seq ) ?
>>
>> If this code is not in the standard library, how about adding it? Seems
>> pretty useful, and not too trivial.
>>
>> What do you say?
>>
>> ---=====---
>> Александр
>>
>> ------------------------------------------------------------
>> ------------------
>> _______________________________________________
>> Factor-talk mailing list
>> Factor-talk@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/factor-talk
>>
>
>
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