John, thank you very much! : )
Really helpful stuff!
18.11.2016, 18:13, "John Benediktsson" <mrj...@gmail.com>:
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 ; inlineThen you can use it:IN: scratchpad { 1 2 3 4 5 } [ 2/ ] duplicates-by{ 1 2 4 }IN: scratchpad sequence-of-tuples [ hash>> ] duplicates-byIt 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?
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