OK I simply fed Jena's source to ChatGPT and asked it to produce an
RDFLIb version :)
No idea if it's correct but I'll find out I guess.
from rdflib import Variable, BNode, Literal
from rdflib.plugins.sparql.algebra import BGP, Filter, Join, LeftJoin,
Union, Graph, Extend, Minus, OrderBy, Project
def substitute(algebra, binding):
if isinstance(algebra, BGP):
new_triples = []
for s, p, o in algebra.triples:
s = binding.get(s, s)
p = binding.get(p, p)
o = binding.get(o, o)
new_triples.append((s, p, o))
return BGP(new_triples)
elif isinstance(algebra, Filter):
new_p = substitute(algebra.p, binding)
new_expr = algebra.expr
for var, val in binding.items():
new_expr = new_expr.substitute(var, val)
return Filter(new_expr, new_p)
elif isinstance(algebra, Join):
return Join(substitute(algebra.p1, binding),
substitute(algebra.p2, binding))
elif isinstance(algebra, LeftJoin):
return LeftJoin(substitute(algebra.p1, binding),
substitute(algebra.p2, binding), algebra.expr)
elif isinstance(algebra, Union):
return Union(substitute(algebra.p1, binding),
substitute(algebra.p2, binding))
elif isinstance(algebra, Graph):
return Graph(algebra.term, substitute(algebra.p, binding))
elif isinstance(algebra, Extend):
new_p = substitute(algebra.p, binding)
new_expr = algebra.expr
for var, val in binding.items():
new_expr = new_expr.substitute(var, val)
return Extend(new_p, new_expr, algebra.var)
elif isinstance(algebra, Minus):
return Minus(substitute(algebra.p1, binding),
substitute(algebra.p2, binding))
elif isinstance(algebra, OrderBy):
return OrderBy(substitute(algebra.p, binding), algebra.expr)
elif isinstance(algebra, Project):
return Project(substitute(algebra.p, binding), algebra.PV)
else:
return algebra
On Thu, Feb 6, 2025 at 12:54 AM Martynas Jusevičius
<marty...@atomgraph.com> wrote:
>
> Hi,
>
> I was looking to implement something like substitute() using RDFLib.
>
> I checked the note:
> https://afs.github.io/substitute.htm
> But I couldn't find a clear example.
>
> For example, how would this query string (the template)
>
> PREFIX dbo: <http://dbpedia.org/ontology/>
> CONSTRUCT
> WHERE { ?city dbo:populationTotal ?population }
>
> would look like after substituting (?city,
> <http://dbpedia.org/resource/Copenhagen>)?
>
>
> Martynas
