owmeta_core.graph_object module

exception owmeta_core.graph_object.IdentifierMissingException(dataObject='[unspecified object]', *args, **kwargs)

Bases: Exception

Indicates that an identifier should be available for the object in question, but there is none

class owmeta_core.graph_object.ComponentTripler(start, traverse_undefined=False, generator=False)

Bases: object

Gets a set of triples that are connected to the given object by objects which have an identifier.

The ComponentTripler does not query against a backing graph, but instead uses the properties attached to the object.

class owmeta_core.graph_object.DescendantTripler(start, graph=None, transitive=True)

Bases: object

Gets triples that the object points to, optionally transitively.

Parameters

startGraphObject

the node to start from

graphrdflib.graph.Graph, optional

if given, the graph to draw descedants from. Otherwise the object graph is used

class owmeta_core.graph_object.GraphObject(**kwargs)

Bases: object

An object which can be included in the object graph.

An abstract base class.

variable()

Must return a Variable object that identifies this GraphObject in queries.

The variable can be randomly generated when the object is created and stored in the object.

property defined

Returns true if an identifier() would return an identifier

property identifier

Must return an object representing this object or else raise an Exception.

class owmeta_core.graph_object.GraphObjectChecker(query_object, graph, sort_first=False)

Bases: object

Checks the graph of defined GraphObjects for

class owmeta_core.graph_object.GraphObjectQuerier(q, graph, hop_scorer=None)

Bases: object

Performs queries for objects in the given graph.

The querier queries for objects at the center of a star graph. In SPARQL, the query has the form:

SELECT ?x WHERE {
    ?x  <p1> ?o1 .
    ?o1 <p2> ?o2 .
     ...
    ?on <pn> <a> .

    ?x  <q1> ?n1 .
    ?n1 <q2> ?n2 .
     ...
    ?nn <qn> <b> .
}

It is allowed that <px> == <py> for x != y.

Queries such as:

SELECT ?x WHERE {
    ?x  <p1> ?o1 .
     ...
    ?on <pn>  ?y .
}

or:

SELECT ?x WHERE {
    ?x  <p1> ?o1 .
     ...
    ?on <pn>  ?x .
}

or:

SELECT ?x WHERE {
    ?x  ?z ?o .
}

or:

SELECT ?x WHERE {
    ?x  ?z <a> .
}

are not supported and will be ignored without error.

Call the GraphObjectQuerier object to perform the query.

Parameters

qGraphObject

The object which is queried on

graphobject

The graph from which the objects are queried. Must implement a method triples() that takes a triple pattern, t, and returns a set of triples matching that pattern. The pattern for t is t[i] = None, 0 <= i <= 2, indicates that the i’th position can take any value.

The graph method can optionally implement the ‘range query’ ‘interface’: the graph must have a property supports_range_queries equal to True and triples() must accept an InRange object in the object position of the query triple, but only for literals

hop_scorercallable()

Returns a score for a hop (a four-tuple, (subject, predicate, object, target)) indicating how selective the query would be for that hop, with lower numbers being more selective. In general the score should only take the given hop into account – it should not take previously given hops into account when calculating a score.

merge_paths(l)

Combines a list of lists into a multi-level table with the elements of the lists as the keys. For given:

[[a, b, c], [a, b, d], [a, e, d]]

merge_paths returns:

{a: {b: {c: {},
         d: {}},
     e: {d: {}}}}

class owmeta_core.graph_object.LegendFinder(start, graph=None)

Bases: object

Gets a list of the objects which can not be deleted freely from the transitive closure.

Essentially, this is the ‘mark’ phase of the “mark-and-sweep” garbage collection algorithm.

“Heroes get remembered, but legends never die.”

class owmeta_core.graph_object.Variable

Bases: int

A marker used in GraphObjectQuerier for variables in a query