- From: Andy Seaborne <andy.seaborne@talis.com>
- Date: Tue, 30 Mar 2010 18:32:09 +0100
- To: Steve Harris <steve.harris@garlik.com>
- CC: SPARQL Working Group <public-rdf-dawg@w3.org>
On 30/03/2010 5:59 PM, Steve Harris wrote: > On 2010-03-30, at 16:52, Andy Seaborne wrote: >> >> On 30/03/2010 3:26 PM, Ivan Mikhailov wrote: >>> Hello Axel, >> ... >> >>>> Would we also allow aggregates with arityy different to 1 (like common in functions) e.g. agg-uri(?X ?Y) >>> >>> That's absolutely required for statistical calculations of all sorts, >>> from regression to likelihood detection. >>> >>> Best Regards, >>> >>> Ivan. >> >> At F2F3, we decided to not restrict the arity to 1 for custom aggregates (and they can have parameters to the aggregator as well as arguments to aggregate over). > > We did? It sounds plausible, but I don't actually remember that. Is it a parser issue? Stats aggregates were the main argument for n-ary custom aggregates. The whole multiset of tuples is based around it as well. Several of the built-ins are 1-ary ; some are n-ary. (and some I'm not clear about). The parser will parse N-ary custom aggregates regardless because a custom aggregate look, syntactically, exactly like a custom function. I don't see why we should not be able to write any built-in as a custom aggregate. We should give URIs the aggregates we do define. Andy > > - Steve >
Received on Tuesday, 30 March 2010 17:32:42 UTC