Merge pull request #7565 from hvy/chx-is-unchained

Introduce `chainerx.ndarray._is_chained`
chainer · Jun 24, 2019 · 3d47091 · 3d47091
2 parents 3c567d3 + cbc11e7
commit 3d47091
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diff --git a/chainerx_cc/chainerx/python/array.cc b/chainerx_cc/chainerx/python/array.cc
@@ -12,6 +12,7 @@
 #include <nonstd/optional.hpp>
 
 #include "chainerx/array.h"
+#include "chainerx/array_body.h"
 #include "chainerx/array_index.h"
 #include "chainerx/axes.h"
 #include "chainerx/backend_util.h"
@@ -635,6 +636,17 @@ void InitChainerxArray(pybind11::module& m) {
 
         return list;
     });
+    // TODO(hvy): Rename `_is_chained` to a less ambiguous function name.
+    c.def("_is_chained",
+          [](const ArrayBodyPtr& self, const nonstd::optional<BackpropId>& backprop_id) {
+              BackpropId actual_backprop_id = internal::GetArrayBackpropId(Array{self}, backprop_id);
+              actual_backprop_id.CheckValid();
+              if (!self->HasArrayNode(actual_backprop_id)) {
+                  throw ChainerxError{"Array is constant with respect to the computation for backprop ID: '", actual_backprop_id, "'."};
+              }
+              return self->GetArrayNode(actual_backprop_id)->creator_op_node() != nullptr;
+          },
+          "backprop_id"_a = nullptr);
 }
 
 }  // namespace python_internal

diff --git a/tests/chainerx_tests/unit_tests/test_array.py b/tests/chainerx_tests/unit_tests/test_array.py
@@ -718,3 +718,15 @@ def test_array_deepcopy(device):
     chainerx.testing.assert_array_equal(
         arr2,
         chainerx.array([1, 2], chainerx.float32))
+
+
+def test_is_chained():
+    arr = chainerx.array([1, 2], chainerx.float32)
+    with pytest.raises(chainerx.ChainerxError):
+        arr._is_chained()
+
+    arr.require_grad()
+    assert not arr._is_chained()
+
+    arr2 = 2 * arr
+    assert arr2._is_chained()