Combining multiple rowsets in SPARQL

Question

I cannot describe my problem formally because of my poor English; let me talk about this using an example. In the table below, "subject", "predicate" are actually grouped.

We define a set by lines if they are the same “subject”. Now I want to combine any two sets if they contain the same "predicate", summarize the "count" of the same "predicate" and count the number of individual items that have the same set.

subject predicate count ----------------------------- s1 p1 1 s1 p2 2 s2 p1 3 s3 p1 2 s3 p2 2 

Therefore, two sets are required from this table:

 {2, (p1, 3), (p2, 4)}, {1, (p1,3)} 

where in the first set 2 indicates that there are two objects (s1 and s3) having this set; (p1,3) is the sum of (s1, p1, 1) and (s3, p1, 2).

So how can I get these sets and save them in Java?

• How to do it with SPARQL?

• Or, firstly, save these triples in Java, then how can I get these sets using Java?

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One solution might be concat predicates and counts,

 SELECT (COUNT(?s) AS ?distinct) ?propset (group_concat(?count; separator = \"\\t\") AS ?counts) { SELECT ?s (group_concat(?p; separator = \" \") AS ?propset) (group_concat(?c; separator = \" \") AS ?count { ?s ?p ?c } GROUP BY ?s ORDER BY ?s } GROUP BY ?propset ORDER BY ?propset 

Then the counts can be divided, then added up. It works great on a small dataset, but a lot of time.

I think I will give up this strange problem. Thank you very much for your reply.

Answer 1

Start with

 select ?predicate (sum(?count) as ?totalcount) { ?subject ?predicate ?count } group by ?predicate 

This is the base bit, but the grouping is incorrect (now being specified).

The grouping variable should be like this (hope this is the correct syntax):

 select ?subject (group_concat(distinct ?p ; separator = ",") AS ?propset) { ?subject ?p ?c } group by ?subject 

Hope this gives:

 subject propset ------------------ s1 "p1,p2" s2 "p1" s3 "p1,p2" 

So, the final request should be:

 select ?predicate (sum(?count) as ?totalcount) { ?subject ?predicate ?count . { select ?subject (group_concat(distinct ?p ; separator = ",") AS ?propset) { ?subject ?p ?c } group by ?subject } } group by ?propset ?predicate 

It works?