feat(mge/functional): add python wrapper to resize opr

GitOrigin-RevId: b7cc6dd829531d750c6d61c9dc316d7999d82cfc

imperative/python/megengine/functional/nn.py

@@ -7,7 +7,7 @@
 # software distributed under the License is distributed on an
 # "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # pylint: disable=too-many-lines
-from typing import Optional, Sequence, Tuple, Union
+from typing import Iterable, Optional, Sequence, Tuple, Union
 
 from ..core._imperative_rt import CompNode
 from ..core._imperative_rt.core2 import apply
@@ -58,6 +58,7 @@ __all__ = [
     "one_hot",
     "prelu",
     "remap",
+    "resize",
     "softmax",
     "softplus",
     "svd",
@@ -878,6 +879,41 @@ def one_hot(inp: Tensor, num_classes: int) -> Tensor:
     return result
 
 
+def resize(
+    inp: Tensor, target_shape: Iterable[int], interp_mode: str = "LINEAR"
+) -> Tensor:
+    r"""
+    Applies resize transformation to batched 2D images.
+
+    :param inp: `(N, C, H, W)` input tensor. Currently only support "NCHW" format.
+    :param target_shape: `(H, W)` target images shape.
+    :param interp_mode: interpolation methods. Defaule mode is "LINEAR", Currently only support "LINEAR".
+
+    Examples:
+
+    .. testcode::
+
+        import numpy as np
+        from megengine import tensor
+        import megengine.functional as F
+
+        x = tensor(np.random.randn(10, 3, 32, 32))
+        out = F.resize(x, (16, 16))
+        print(out.numpy().shape)
+
+    Outputs:
+
+    .. testoutput::
+
+        (10, 3, 16, 16)
+
+    """
+    op = builtin.Resize(imode=interp_mode, format="NCHW")
+    shape = astensor1d(target_shape, inp, dtype="int32", device=inp.device)
+    (result,) = apply(op, inp, shape)
+    return result
+
+
 def warp_perspective(
     inp: Tensor,
     M: Tensor,

imperative/python/test/unit/core/test_autodiff.py

@@ -373,6 +373,17 @@ def test_Broadcast():
     np.testing.assert_equal(np.ones((3, 3, 1), dtype=np.float32) * 10, x.grad.numpy())
 
 
+def test_resize():
+    x_np = np.random.rand(3, 3, 32, 32).astype("float32")
+    x = mge.Tensor(x_np)
+
+    grad = Grad().wrt(x, callback=save_to(x))
+    y = F.resize(x, (16, 16))
+
+    grad(y, F.ones_like(y))
+    np.testing.assert_equal(np.ones(x_np.shape, dtype=np.float32) / 4, x.grad.numpy())
+
+
 def test_Reduce_sum():
     x_np = np.random.rand(3, 3).astype("float32")
     x = mge.Tensor(x_np)

imperative/python/test/unit/functional/test_functional.py

@@ -328,6 +328,31 @@ def test_one_hot():
     onehot_high_dimension()
 
 
+def test_resize():
+    # check shape
+    test_cases = [
+        [(1, 1, 10, 10), (5, 5)],
+        [(1, 3, 10, 10), (20, 20)],
+        [(10, 1, 10, 10), (1, 1)],
+        [(10, 10, 1, 1), (10, 10)],
+    ]
+    for inp_shape, target_shape in test_cases:
+        x = tensor(np.random.randn(*inp_shape), dtype=np.float32)
+        out = F.resize(x, target_shape, interp_mode="LINEAR")
+        assert out.shape[0] == x.shape[0] and out.shape[1] == x.shape[1]
+        assert out.shape[2] == target_shape[0] and out.shape[3] == target_shape[1]
+
+    # check value
+    x = tensor(np.ones((3, 3, 10, 10)), dtype=np.float32)
+    out = F.resize(x, (15, 5), interp_mode="LINEAR")
+    np.testing.assert_equal(out.numpy(), np.ones((3, 3, 15, 5)).astype(np.float32))
+
+    np_x = np.arange(32)
+    x = tensor(np_x).astype(np.float32).reshape(1, 1, 32, 1)
+    out = F.resize(x, (1, 1), interp_mode="LINEAR")
+    np.testing.assert_equal(out.item(), np_x.mean())
+
+
 def test_warp_perspective():
     inp_shape = (1, 1, 4, 4)
     x = tensor(np.arange(16, dtype=np.float32).reshape(inp_shape))

imperative/src/impl/ops/resize.cpp

+/**
+ * \file imperative/src/impl/ops/resize.cpp
+ * MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
+ *
+ * Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ */
+
+#include "megbrain/imperative/ops/autogen.h"
+#include "megbrain/opr/imgproc.h"
+
+#include "../op_trait.h"
+
+namespace mgb {
+namespace imperative {
+
+namespace {
+
+auto apply_on_var_node(
+        const OpDef& def,
+        const VarNodeArray& inputs) {
+    auto&& op = static_cast<const Resize&>(def);
+    mgb_assert(inputs.size() == 2);
+    return opr::Resize::make(inputs[0], inputs[1], op.param());
+}
+
+OP_TRAIT_REG(Resize, Resize)
+    .apply_on_var_node(apply_on_var_node)
+    .fallback();
+} // anonymous namespace
+
+}  // namespace imperative
+}  // namespace mgb
+
+// vim: syntax=cpp.doxygen foldmethod=marker foldmarker=f{{{,f}}}

src/core/include/megbrain/ir/ops.td

@@ -76,6 +76,8 @@ def WarpPerspective: MgbHashableOp<"WarpPerspective", [WarpPerspectiveParam]>;
 
 def Remap: MgbHashableOp<"Remap", [RemapParam]>;
 
+def Resize: MgbHashableOp<"Resize", [ResizeParam]>;
+
 def IndexingOneHot: MgbHashableOp<"IndexingOneHot", [AxisParam]>;
 
 def IndexingSetOneHot: MgbHashableOp<"IndexingSetOneHot", [AxisParam]>;