add variable_depends_on

pytensor/graph/basic.py

@@ -1603,6 +1603,28 @@ def apply_depends_on(apply: Apply, depends_on: Union[Apply, Collection[Apply]])
     return False
 
 
+def variable_depends_on(
+    variable: Variable, depends_on: Union[Variable, Collection[Variable]]
+) -> bool:
+    """Determine if any `depends_on` is in the graph given by ``variable``.
+    Parameters
+    ----------
+    variable: Variable
+        Node to check
+    depends_on: Collection[Variable]
+        Nodes to check dependency on
+
+    Returns
+    -------
+    bool
+    """
+    if not isinstance(depends_on, Collection):
+        depends_on = {depends_on}
+    else:
+        depends_on = set(depends_on)
+    return any(interim in depends_on for interim in ancestors([variable]))
+
+
 def equal_computations(
     xs: List[Union[np.ndarray, Variable]],
     ys: List[Union[np.ndarray, Variable]],

tests/graph/test_basic.py

@@ -23,6 +23,7 @@ from pytensor.graph.basic import (
     io_toposort,
     list_of_nodes,
     orphans_between,
+    variable_depends_on,
     vars_between,
     walk,
 )
@@ -675,3 +676,22 @@ def test_NominalVariable_create_variable_type():
     assert type(ntv_unpkld) is type(ntv)
     assert ntv_unpkld.equals(ntv)
     assert ntv_unpkld is ntv
+
+
+def test_variable_depends_on():
+    x = MyVariable(1)
+    x.name = "x"
+    y = MyVariable(1)
+    y.name = "y"
+    x2 = MyOp(x)
+    x2.name = "x2"
+    y2 = MyOp(y)
+    y2.name = "y2"
+    o = MyOp(x2, y)
+    assert variable_depends_on(o, x)
+    assert variable_depends_on(o, [x])
+    assert not variable_depends_on(o, [y2])
+    assert variable_depends_on(o, [y2, x])
+    assert not variable_depends_on(y, [y2])
+    assert variable_depends_on(y, [y])
+