From ffd736e27ac5d5c9889c0b756b10055cb4528d7b Mon Sep 17 00:00:00 2001
From: HongYu <20734616+james77777778@users.noreply.github.com>
Date: Tue, 19 Sep 2023 12:47:41 +0800
Subject: [PATCH] Makes `ops.split` in torch consistent with other backends
 (#914)

* Makes split in torch consistent with other backends

* Update error msg
---
 keras_core/backend/torch/numpy.py | 18 +++++++++--
 keras_core/ops/numpy_test.py      | 53 +++++++++++--------------------
 2 files changed, 34 insertions(+), 37 deletions(-)

diff --git a/keras_core/backend/torch/numpy.py b/keras_core/backend/torch/numpy.py
index ba613cfcd..4986320f6 100644
--- a/keras_core/backend/torch/numpy.py
+++ b/keras_core/backend/torch/numpy.py
@@ -800,22 +800,34 @@ def sort(x, axis=-1):
 
 def split(x, indices_or_sections, axis=0):
     x = convert_to_tensor(x)
+    dim = x.shape[axis]
     if isinstance(indices_or_sections, (list, tuple)):
         idxs = convert_to_tensor(indices_or_sections)
         start_size = indices_or_sections[0]
-        end_size = x.shape[axis] - indices_or_sections[-1]
+        end_size = dim - indices_or_sections[-1]
         chunk_sizes = (
             [start_size]
             + torch.diff(idxs).type(torch.int).tolist()
             + [end_size]
         )
     else:
-        chunk_sizes = x.shape[axis] // indices_or_sections
-    return torch.split(
+        if dim % indices_or_sections != 0:
+            raise ValueError(
+                f"Received indices_or_sections={indices_or_sections} "
+                f"(interpreted as a number of sections) and axis={axis}, "
+                f"but input dimension x.shape[{axis}]={x.shape[axis]} "
+                f"is not divisible by {indices_or_sections}. "
+                f"Full input shape: x.shape={x.shape}"
+            )
+        chunk_sizes = dim // indices_or_sections
+    out = torch.split(
         tensor=x,
         split_size_or_sections=chunk_sizes,
         dim=axis,
     )
+    if dim == 0 and isinstance(indices_or_sections, int):
+        out = tuple(out[0].clone() for _ in range(indices_or_sections))
+    return out
 
 
 def stack(x, axis=0):
diff --git a/keras_core/ops/numpy_test.py b/keras_core/ops/numpy_test.py
index 0ff0d364b..2ae7f12c6 100644
--- a/keras_core/ops/numpy_test.py
+++ b/keras_core/ops/numpy_test.py
@@ -3283,40 +3283,25 @@ def test_sort(self):
 
     def test_split(self):
         x = np.array([[1, 2, 3], [3, 2, 1]])
-        if backend.backend() == "torch":
-            self.assertAllClose(
-                [backend.convert_to_numpy(t) for t in knp.split(x, 2)],
-                np.split(x, 2),
-            )
-            self.assertAllClose(
-                [backend.convert_to_numpy(t) for t in knp.Split(2)(x)],
-                np.split(x, 2),
-            )
-            self.assertAllClose(
-                [
-                    backend.convert_to_numpy(t)
-                    for t in knp.split(x, [1, 2], axis=1)
-                ],
-                np.split(x, [1, 2], axis=1),
-            )
-            self.assertAllClose(
-                [
-                    backend.convert_to_numpy(t)
-                    for t in knp.Split([1, 2], axis=1)(x)
-                ],
-                np.split(x, [1, 2], axis=1),
-            )
-        else:
-            self.assertAllClose(knp.split(x, 2), np.split(x, 2))
-            self.assertAllClose(knp.Split(2)(x), np.split(x, 2))
-            self.assertAllClose(
-                knp.split(x, [1, 2], axis=1),
-                np.split(x, [1, 2], axis=1),
-            )
-            self.assertAllClose(
-                knp.Split([1, 2], axis=1)(x),
-                np.split(x, [1, 2], axis=1),
-            )
+        self.assertAllClose(knp.split(x, 2), np.split(x, 2))
+        self.assertAllClose(knp.Split(2)(x), np.split(x, 2))
+        self.assertAllClose(
+            knp.split(x, [1, 2], axis=1),
+            np.split(x, [1, 2], axis=1),
+        )
+        self.assertAllClose(
+            knp.Split([1, 2], axis=1)(x),
+            np.split(x, [1, 2], axis=1),
+        )
+
+        # test invalid indices_or_sections
+        with self.assertRaises(Exception):
+            knp.split(x, 3)
+
+        # test zero dimension
+        x = np.ones(shape=(0,))
+        self.assertEqual(len(knp.split(x, 2)), 2)
+        self.assertEqual(len(knp.Split(2)(x)), 2)
 
     def test_sqrt(self):
         x = np.array([[1, 4, 9], [16, 25, 36]])