Add keep_predicates filter

src/curies/triples/__init__.py

@@ -139,6 +139,7 @@
     exclude_subject_prefixes,
     exclude_triples,
     keep_object_prefixes,
+    keep_predicates,
     keep_prefixes_both,
     keep_prefixes_either,
     keep_references_both,
@@ -164,6 +165,7 @@
     "exclude_triples",
     "hash_triple",
     "keep_object_prefixes",
+    "keep_predicates",
     "keep_prefixes_both",
     "keep_prefixes_either",
     "keep_references_both",

src/curies/triples/filters.py

@@ -16,6 +16,7 @@
     "exclude_subject_prefixes",
     "exclude_triples",
     "keep_object_prefixes",
+    "keep_predicates",
     "keep_prefixes_both",
     "keep_prefixes_either",
     "keep_references_both",
@@ -546,3 +547,47 @@ def _func(triple: TripleType) -> bool:
         return triple.subject not in references and triple.object not in references
 
     return _func
+
+
+def keep_predicates(
+    triples: Iterable[TripleType],
+    predicates: Reference | Collection[Reference],
+    *,
+    progress: bool = False,
+) -> Iterable[TripleType]:
+    """Keep triples whose predicate appear in the given references.
+
+    :param triples: An iterable of triples
+    :param predicates: A collection of references
+    :param progress: Should a progress bar be shown?
+
+    :returns: A sub-iterable of triples whose predicate appear in the given
+        references.
+
+    >>> from curies import Reference, Triple
+    >>> from curies.vocabulary import exact_match, subclass_of
+    >>> c1, c2, c3 = "DOID:0050577", "mesh:C562966", "DOID:225"
+    >>> r1, r2, r3 = (Reference.from_curie(c) for c in (c1, c2, c3))
+    >>> m1 = Triple.from_curies(c1, exact_match.curie, c2)
+    >>> m2 = Triple.from_curies(c2, exact_match.curie, c3)
+    >>> m3 = Triple.from_curies(c1, subclass_of.curie, c3)
+    >>> assert list(keep_predicates([m1, m2, m3], exact_match)) == [m1, m2]
+    """
+    return _filter(_include_predicates(predicates), triples, progress=progress)
+
+
+def _include_predicates(
+    predicates: Reference | Collection[Reference],
+) -> TriplePredicate[TripleType]:
+    if isinstance(predicates, Reference):
+
+        def _func(triple: TripleType) -> bool:
+            return triple.predicate == predicates
+
+    else:
+        predicates = set(predicates)
+
+        def _func(triple: TripleType) -> bool:
+            return triple.predicate in predicates
+
+    return _func

tests/test_triples/test_filter.py

@@ -12,6 +12,7 @@
     exclude_subject_prefixes,
     exclude_triples,
     keep_object_prefixes,
+    keep_predicates,
     keep_prefixes_both,
     keep_prefixes_either,
     keep_references_both,
@@ -149,3 +150,11 @@ def test_exclude_references(self) -> None:
         self.assert_triple_lists([m2], exclude_references_both(M123, [r1]))
         self.assert_triple_lists([m3], exclude_references_both(M123, [r2]))
         self.assert_triple_lists([m1], exclude_references_both(M123, [r3]))
+
+    def test_keep_predicate(self) -> None:
+        """Test keep predicate."""
+        self.assert_triple_lists([m1, m2, m3], keep_predicates([m1, m2, m3, m4], exact_match))
+        self.assert_triple_lists([m1, m2, m3], keep_predicates([m1, m2, m3, m4], [exact_match]))
+        self.assert_triple_lists(
+            [m1, m2, m3, m4], keep_predicates([m1, m2, m3, m4], [exact_match, subclass_of])
+        )