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fix: aggregate undirected SQL degrees #82

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Merged
j6k4m8 merged 1 commit into from
Jul 27, 2026
Merged

fix: aggregate undirected SQL degrees #82

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64 changes: 40 additions & 24 deletions grand/backends/_sqlbackend.py
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Original file line number Diff line number Diff line change
Expand Up @@ -711,6 +711,9 @@ def out_degrees(self, nbunch=None):

"""

if not self._directed:
return self._undirected_degrees(nbunch)

if nbunch is None:
where_clause = None
elif isinstance(nbunch, (list, tuple)):
Expand All @@ -721,18 +724,11 @@ def out_degrees(self, nbunch=None):
# single node:
where_clause = self._edge_table.c[self._edge_source_key] == str(nbunch)

if self._directed:
query = (
select(self._edge_table.c[self._edge_source_key], func.count())
.select_from(self._edge_table)
.group_by(self._edge_table.c[self._edge_source_key])
)
else:
query = (
select(self._edge_table.c[self._edge_source_key], func.count())
.select_from(self._edge_table)
.group_by(self._edge_table.c[self._edge_source_key])
)
query = (
select(self._edge_table.c[self._edge_source_key], func.count())
.select_from(self._edge_table)
.group_by(self._edge_table.c[self._edge_source_key])
)

if where_clause is not None:
query = query.where(where_clause)
Expand All @@ -755,6 +751,9 @@ def in_degrees(self, nbunch=None):

"""

if not self._directed:
return self._undirected_degrees(nbunch)

if nbunch is None:
where_clause = None
elif isinstance(nbunch, (list, tuple)):
Expand All @@ -765,18 +764,11 @@ def in_degrees(self, nbunch=None):
# single node:
where_clause = self._edge_table.c[self._edge_target_key] == str(nbunch)

if self._directed:
query = (
select(self._edge_table.c[self._edge_target_key], func.count())
.select_from(self._edge_table)
.group_by(self._edge_table.c[self._edge_target_key])
)
else:
query = (
select(self._edge_table.c[self._edge_target_key], func.count())
.select_from(self._edge_table)
.group_by(self._edge_table.c[self._edge_target_key])
)
query = (
select(self._edge_table.c[self._edge_target_key], func.count())
.select_from(self._edge_table)
.group_by(self._edge_table.c[self._edge_target_key])
)

if where_clause is not None:
query = query.where(where_clause)
Expand All @@ -787,6 +779,30 @@ def in_degrees(self, nbunch=None):
return results.get(nbunch, 0)
return results

def _undirected_degrees(self, nbunch=None):
endpoints = select(
self._edge_table.c[self._edge_source_key].label("node")
).union_all(
select(self._edge_table.c[self._edge_target_key].label("node"))
).subquery()
query = select(endpoints.c.node, func.count()).group_by(endpoints.c.node)

requested = None
if isinstance(nbunch, (list, tuple)):
requested = list(nbunch)
query = query.where(
endpoints.c.node.in_([str(node) for node in requested])
)
elif nbunch is not None:
query = query.where(endpoints.c.node == str(nbunch))

results = {row[0]: row[1] for row in self._connection.execute(query)}
if requested is not None:
return {node: results.get(str(node), 0) for node in requested}
if nbunch is not None:
return results.get(str(nbunch), 0)
return results

def ingest_from_edgelist_dataframe(
self, edgelist: pd.DataFrame, source_column: str, target_column: str
) -> dict:
Expand Down
28 changes: 28 additions & 0 deletions grand/backends/test_sql_transactions.py
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Original file line number Diff line number Diff line change
Expand Up @@ -327,3 +327,31 @@ def test_legacy_sql_edge_remains_readable(tmp_path):
assert backend.get_edge_by_id("A", "B") == {"old": True}
assert backend.get_edge_count() == 1
backend.close()


def test_undirected_sql_degrees_aggregate_both_edge_orientations(tmp_path):
backend = SQLBackend(
db_url=f"sqlite:///{tmp_path / 'graph.db'}", directed=False
)
backend.add_edges_from([("A", "B"), ("C", "A")])

expected = {"A": 2, "B": 1, "C": 1}
assert backend.out_degrees() == expected
assert backend.in_degrees() == expected
backend.close()


def test_undirected_sql_degrees_include_requested_zero_degree_nodes(tmp_path):
backend = SQLBackend(
db_url=f"sqlite:///{tmp_path / 'graph.db'}", directed=False
)
backend.add_nodes_from([("D", {})])
backend.add_edges_from([("A", "B"), ("C", "A")])

expected = {"A": 2, "B": 1, "C": 1, "D": 0}
assert backend.out_degrees(["A", "B", "C", "D"]) == expected
assert backend.in_degrees(["A", "B", "C", "D"]) == expected
assert backend.out_degrees("D") == 0
assert backend.in_degrees("D") == 0
assert backend.out_degrees([1]) == {1: 0}
backend.close()
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