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collection

Classes:

__all__ module-attribute 

__all__ = ['Collection']

Collection 

Collection(graph: Graph, uri: Node, seq: List[Node] = [])

See “Emulating container types”: https://docs.python.org/reference/datamodel.html#emulating-container-types

>>> from rdflib.term import Literal
>>> from rdflib.graph import Graph
>>> from pprint import pprint
>>> listname = BNode()
>>> g = Graph('Memory')
>>> listItem1 = BNode()
>>> listItem2 = BNode()
>>> g.add((listname, RDF.first, Literal(1))) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((listname, RDF.rest, listItem1)) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((listItem1, RDF.first, Literal(2))) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((listItem1, RDF.rest, listItem2)) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((listItem2, RDF.rest, RDF.nil)) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((listItem2, RDF.first, Literal(3))) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> c = Collection(g,listname)
>>> pprint([term.n3() for term in c])
['"1"^^<http://www.w3.org/2001/XMLSchema#integer>',
 '"2"^^<http://www.w3.org/2001/XMLSchema#integer>',
 '"3"^^<http://www.w3.org/2001/XMLSchema#integer>']
>>> Literal(1) in c
True
>>> len(c)
3
>>> c._get_container(1) == listItem1
True
>>> c.index(Literal(2)) == 1
True

The collection is immutable if uri is the empty list (http://www.w3.org/1999/02/22-rdf-syntax-ns#nil).

Methods:

Attributes:

Source code in rdflib/collection.py 
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def __init__(self, graph: Graph, uri: Node, seq: List[Node] = []):
    self.graph = graph
    self.uri = uri or BNode()
    if seq:
        self += seq

graph instance-attribute 

graph = graph

uri instance-attribute 

uri = uri or BNode()

__delitem__ 

__delitem__(key: int) -> None

>>> from rdflib.namespace import RDF, RDFS
>>> from rdflib import Graph
>>> from pprint import pformat
>>> g = Graph()
>>> a = BNode('foo')
>>> b = BNode('bar')
>>> c = BNode('baz')
>>> g.add((a, RDF.first, RDF.type)) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((a, RDF.rest, b)) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((b, RDF.first, RDFS.label)) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((b, RDF.rest, c)) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((c, RDF.first, RDFS.comment)) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((c, RDF.rest, RDF.nil)) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> len(g)
6
>>> def listAncestry(node, graph):
...   for i in graph.subjects(RDF.rest, node):
...     yield i
>>> [str(node.n3())
...   for node in g.transitiveClosure(listAncestry, RDF.nil)]
['_:baz', '_:bar', '_:foo']
>>> lst = Collection(g, a)
>>> len(lst)
3
>>> b == lst._get_container(1)
True
>>> c == lst._get_container(2)
True
>>> del lst[1]
>>> len(lst)
2
>>> len(g)
4
Source code in rdflib/collection.py 
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def __delitem__(self, key: int) -> None:
    """
    ```python
    >>> from rdflib.namespace import RDF, RDFS
    >>> from rdflib import Graph
    >>> from pprint import pformat
    >>> g = Graph()
    >>> a = BNode('foo')
    >>> b = BNode('bar')
    >>> c = BNode('baz')
    >>> g.add((a, RDF.first, RDF.type)) # doctest: +ELLIPSIS
    <Graph identifier=... (<class 'rdflib.graph.Graph'>)>
    >>> g.add((a, RDF.rest, b)) # doctest: +ELLIPSIS
    <Graph identifier=... (<class 'rdflib.graph.Graph'>)>
    >>> g.add((b, RDF.first, RDFS.label)) # doctest: +ELLIPSIS
    <Graph identifier=... (<class 'rdflib.graph.Graph'>)>
    >>> g.add((b, RDF.rest, c)) # doctest: +ELLIPSIS
    <Graph identifier=... (<class 'rdflib.graph.Graph'>)>
    >>> g.add((c, RDF.first, RDFS.comment)) # doctest: +ELLIPSIS
    <Graph identifier=... (<class 'rdflib.graph.Graph'>)>
    >>> g.add((c, RDF.rest, RDF.nil)) # doctest: +ELLIPSIS
    <Graph identifier=... (<class 'rdflib.graph.Graph'>)>
    >>> len(g)
    6
    >>> def listAncestry(node, graph):
    ...   for i in graph.subjects(RDF.rest, node):
    ...     yield i
    >>> [str(node.n3())
    ...   for node in g.transitiveClosure(listAncestry, RDF.nil)]
    ['_:baz', '_:bar', '_:foo']
    >>> lst = Collection(g, a)
    >>> len(lst)
    3
    >>> b == lst._get_container(1)
    True
    >>> c == lst._get_container(2)
    True
    >>> del lst[1]
    >>> len(lst)
    2
    >>> len(g)
    4

    ```
    """
    self[key]  # to raise any potential key exceptions
    graph = self.graph
    current = self._get_container(key)
    assert current
    if len(self) == 1 and key > 0:
        pass
    elif key == len(self) - 1:
        # the tail
        priorlink = self._get_container(key - 1)
        # type error: Argument 1 to "set" of "Graph" has incompatible type "Tuple[Optional[Node], URIRef, URIRef]"; expected "Tuple[Node, Node, Any]"
        self.graph.set((priorlink, RDF.rest, RDF.nil))  # type: ignore[arg-type]
        graph.remove((current, None, None))
    else:
        next = self._get_container(key + 1)
        prior = self._get_container(key - 1)
        assert next and prior
        graph.remove((current, None, None))
        graph.set((prior, RDF.rest, next))

__getitem__ 

__getitem__(key: int) -> Node

TODO

Source code in rdflib/collection.py 
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def __getitem__(self, key: int) -> Node:
    """TODO"""
    c = self._get_container(key)
    if c:
        v = self.graph.value(c, RDF.first)
        if v:
            return v
        else:
            raise KeyError(key)
    else:
        raise IndexError(key)

__iadd__ 

__iadd__(other: Iterable[Node])
Source code in rdflib/collection.py 
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def __iadd__(self, other: Iterable[Node]):
    end = self._end()
    if end == RDF.nil:
        raise ValueError("Cannot append to empty list")
    self.graph.remove((end, RDF.rest, None))

    for item in other:
        if (end, RDF.first, None) in self.graph:
            nxt = BNode()
            self.graph.add((end, RDF.rest, nxt))
            end = nxt

        self.graph.add((end, RDF.first, item))

    self.graph.add((end, RDF.rest, RDF.nil))
    return self

__iter__ 

__iter__() -> Iterator[Node]

Iterator over items in Collections

Source code in rdflib/collection.py 
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def __iter__(self) -> Iterator[Node]:
    """Iterator over items in Collections"""
    return self.graph.items(self.uri)

__len__ 

__len__() -> int

length of items in collection.

Source code in rdflib/collection.py 
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def __len__(self) -> int:
    """length of items in collection."""
    return len(list(self.graph.items(self.uri)))

__setitem__ 

__setitem__(key: int, value: Node) -> None

TODO

Source code in rdflib/collection.py 
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def __setitem__(self, key: int, value: Node) -> None:
    """TODO"""
    c = self._get_container(key)
    if c:
        self.graph.set((c, RDF.first, value))
    else:
        raise IndexError(key)

append 

append(item: Node) -> Collection

>>> from rdflib.term import Literal
>>> from rdflib.graph import Graph
>>> listname = BNode()
>>> g = Graph()
>>> c = Collection(g,listname,[Literal(1),Literal(2)])
>>> links = [
...     list(g.subjects(object=i, predicate=RDF.first))[0] for i in c]
>>> len([i for i in links if (i, RDF.rest, RDF.nil) in g])
1
Source code in rdflib/collection.py 
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def append(self, item: Node) -> Collection:
    """
    ```python
    >>> from rdflib.term import Literal
    >>> from rdflib.graph import Graph
    >>> listname = BNode()
    >>> g = Graph()
    >>> c = Collection(g,listname,[Literal(1),Literal(2)])
    >>> links = [
    ...     list(g.subjects(object=i, predicate=RDF.first))[0] for i in c]
    >>> len([i for i in links if (i, RDF.rest, RDF.nil) in g])
    1

    ```
    """
    end = self._end()
    if end == RDF.nil:
        raise ValueError("Cannot append to empty list")

    if (end, RDF.first, None) in self.graph:
        # append new node to the end of the linked list
        node = BNode()
        self.graph.set((end, RDF.rest, node))
        end = node

    self.graph.add((end, RDF.first, item))
    self.graph.add((end, RDF.rest, RDF.nil))
    return self

clear 

clear()
Source code in rdflib/collection.py 
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def clear(self):
    container: Optional[Node] = self.uri
    graph = self.graph
    while container:
        rest = graph.value(container, RDF.rest)
        graph.remove((container, RDF.first, None))
        graph.remove((container, RDF.rest, None))
        container = rest
    return self

index 

index(item: Node) -> int

Returns the 0-based numerical index of the item in the list

Source code in rdflib/collection.py 
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def index(self, item: Node) -> int:
    """
    Returns the 0-based numerical index of the item in the list
    """
    listname = self.uri
    index = 0
    while True:
        if (listname, RDF.first, item) in self.graph:
            return index
        else:
            newlink = list(self.graph.objects(listname, RDF.rest))
            index += 1
            if newlink == [RDF.nil]:
                raise ValueError("%s is not in %s" % (item, self.uri))
            elif not newlink:
                raise Exception("Malformed RDF Collection: %s" % self.uri)
            else:
                assert len(newlink) == 1, "Malformed RDF Collection: %s" % self.uri
                listname = newlink[0]

n3 

n3() -> str

>>> from rdflib.term import Literal
>>> from rdflib.graph import Graph
>>> listname = BNode()
>>> g = Graph('Memory')
>>> listItem1 = BNode()
>>> listItem2 = BNode()
>>> g.add((listname, RDF.first, Literal(1))) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((listname, RDF.rest, listItem1)) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((listItem1, RDF.first, Literal(2))) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((listItem1, RDF.rest, listItem2)) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((listItem2, RDF.rest, RDF.nil)) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> g.add((listItem2, RDF.first, Literal(3))) # doctest: +ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> c = Collection(g, listname)
>>> print(c.n3()) #doctest: +NORMALIZE_WHITESPACE
( "1"^^<http://www.w3.org/2001/XMLSchema#integer>
    "2"^^<http://www.w3.org/2001/XMLSchema#integer>
    "3"^^<http://www.w3.org/2001/XMLSchema#integer> )
Source code in rdflib/collection.py 
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def n3(self) -> str:
    """
    ```python
    >>> from rdflib.term import Literal
    >>> from rdflib.graph import Graph
    >>> listname = BNode()
    >>> g = Graph('Memory')
    >>> listItem1 = BNode()
    >>> listItem2 = BNode()
    >>> g.add((listname, RDF.first, Literal(1))) # doctest: +ELLIPSIS
    <Graph identifier=... (<class 'rdflib.graph.Graph'>)>
    >>> g.add((listname, RDF.rest, listItem1)) # doctest: +ELLIPSIS
    <Graph identifier=... (<class 'rdflib.graph.Graph'>)>
    >>> g.add((listItem1, RDF.first, Literal(2))) # doctest: +ELLIPSIS
    <Graph identifier=... (<class 'rdflib.graph.Graph'>)>
    >>> g.add((listItem1, RDF.rest, listItem2)) # doctest: +ELLIPSIS
    <Graph identifier=... (<class 'rdflib.graph.Graph'>)>
    >>> g.add((listItem2, RDF.rest, RDF.nil)) # doctest: +ELLIPSIS
    <Graph identifier=... (<class 'rdflib.graph.Graph'>)>
    >>> g.add((listItem2, RDF.first, Literal(3))) # doctest: +ELLIPSIS
    <Graph identifier=... (<class 'rdflib.graph.Graph'>)>
    >>> c = Collection(g, listname)
    >>> print(c.n3()) #doctest: +NORMALIZE_WHITESPACE
    ( "1"^^<http://www.w3.org/2001/XMLSchema#integer>
        "2"^^<http://www.w3.org/2001/XMLSchema#integer>
        "3"^^<http://www.w3.org/2001/XMLSchema#integer> )

    ```
    """
    return "( %s )" % (" ".join([i.n3() for i in self]))