[Clean Fluid API]Remove API: gather_nd (#47956)

* Replace paddle.fluid.layers.gather_nd with paddle.gather_nd

* replace gather_nd with paddle.gather_nd

* fix the call of gather_nd

* fix code style of gather_nd

python/paddle/fluid/layers/nn.py

@@ -101,7 +101,6 @@ __all__ = [
     'resize_bilinear',
     'resize_trilinear',
     'resize_nearest',
-    'gather_nd',
     'relu',
     'log',
     'prelu',
@@ -6017,104 +6016,6 @@ def resize_nearest(
     )
 
 
-@deprecated(since="2.0.0", update_to="paddle.gather_nd")
-def gather_nd(input, index, name=None):
-    """
-    **Gather Nd Layer**
-
-    This function is actually a high-dimensional extension of :code:`gather`
-    and supports for simultaneous indexing by multiple axes. :attr:`index` is a
-    K-dimensional integer tensor, which is regarded as a (K-1)-dimensional
-    tensor of :attr:`index` into :attr:`input`, where each element defines
-    a slice of params:
-
-    .. math::
-
-        output[(i_0, ..., i_{K-2})] = input[index[(i_0, ..., i_{K-2})]]
-
-    Obviously, :code:`index.shape[-1] <= input.rank` . And, the output tensor has
-    shape :code:`index.shape[:-1] + input.shape[index.shape[-1]:]` .
-
-    .. code-block:: text
-
-            Given:
-                input = [[[ 0,  1,  2,  3],
-                          [ 4,  5,  6,  7],
-                          [ 8,  9, 10, 11]],
-                         [[12, 13, 14, 15],
-                          [16, 17, 18, 19],
-                          [20, 21, 22, 23]]]
-                input.shape = (2, 3, 4)
-
-            * Case 1:
-                index = [[1]]
-
-                gather_nd(input, index)
-                         = [input[1, :, :]]
-                         = [[12, 13, 14, 15],
-                            [16, 17, 18, 19],
-                            [20, 21, 22, 23]]
-
-            * Case 2:
-                index = [[0,2]]
-
-                gather_nd(input, index)
-                         = [input[0, 2, :]]
-                         = [8, 9, 10, 11]
-
-            * Case 3:
-                index = [[1, 2, 3]]
-
-                gather_nd(input, index)
-                         = [input[1, 2, 3]]
-                         = [23]
-
-    Args:
-        input (Tensor): The input Tensor which it's data type should be bool, float32, float64, int32, int64.
-        index (Tensor): The index input with rank > 1, index.shape[-1] <= input.rank.
-                        Its dtype should be int32, int64.
-        name(str, optional): The default value is None.  Normally there is no need for user to set this property.
-                        For more information, please refer to :ref:`api_guide_Name` .
-
-    Returns:
-        output (Tensor): A tensor with the shape index.shape[:-1] + input.shape[index.shape[-1]:]
-
-    Examples:
-
-        .. code-block:: python
-
-            import paddle
-            import paddle.fluid as fluid
-            paddle.enable_static()
-
-            x = fluid.data(name='x', shape=[3, 4, 5], dtype='float32')
-            index = fluid.data(name='index', shape=[2, 2], dtype='int32')
-            output = fluid.layers.gather_nd(x, index)
-
-    """
-    if in_dygraph_mode():
-        return _C_ops.gather_nd(input, index)
-    else:
-        if _in_legacy_dygraph():
-            return _legacy_C_ops.gather_nd(input, index)
-    check_variable_and_dtype(
-        input,
-        'input',
-        ['bool', 'float32', 'float64', 'int16', 'int32', 'int64'],
-        'gather_np',
-    )
-    check_variable_and_dtype(index, 'index', ['int32', 'int64'], 'gather_np')
-    helper = LayerHelper('gather_nd', **locals())
-    dtype = helper.input_dtype()
-    output = helper.create_variable_for_type_inference(dtype)
-    helper.append_op(
-        type="gather_nd",
-        inputs={"X": input, "Index": index},
-        outputs={"Out": output},
-    )
-    return output
-
-
 def log(x, name=None):
     r"""
     Calculates the natural log of the given input tensor, element-wise.

python/paddle/fluid/layers/rnn.py

@@ -1167,7 +1167,7 @@ class BeamSearchDecoder(Decoder):
         )
         topk_coordinates = paddle.stack([batch_pos, indices], axis=2)
         topk_coordinates.stop_gradient = True
-        return nn.gather_nd(x, topk_coordinates)
+        return paddle.gather_nd(x, topk_coordinates)
 
     class OutputWrapper(
         collections.namedtuple(

python/paddle/fluid/tests/unittests/dygraph_to_static/seq2seq_dygraph_model.py

@@ -199,7 +199,7 @@ class BaseModel(fluid.dygraph.Layer):
 
     def _gather(self, x, indices, batch_pos):
         topk_coordinates = paddle.stack([batch_pos, indices], axis=2)
-        return fluid.layers.gather_nd(x, topk_coordinates)
+        return paddle.gather_nd(x, topk_coordinates)
 
     @declarative
     def forward(self, inputs):
@@ -684,7 +684,7 @@ class AttentionModel(fluid.dygraph.Layer):
 
     def _gather(self, x, indices, batch_pos):
         topk_coordinates = paddle.stack([batch_pos, indices], axis=2)
-        return fluid.layers.gather_nd(x, topk_coordinates)
+        return paddle.gather_nd(x, topk_coordinates)
 
     def attention(self, query, enc_output, mask=None):
         query = fluid.layers.unsqueeze(query, [1])

python/paddle/fluid/tests/unittests/dygraph_to_static/transformer_dygraph_model.py

@@ -768,7 +768,7 @@ class Transformer(Layer):
 
         def gather(input, indices, batch_pos):
             topk_coordinates = paddle.stack([batch_pos, indices], axis=2)
-            return layers.gather_nd(input, topk_coordinates)
+            return paddle.gather_nd(input, topk_coordinates)
 
         # run encoder
         enc_output = self.encoder(src_word, src_pos, src_slf_attn_bias)

python/paddle/fluid/tests/unittests/ir/inference/test_trt_gather_nd_op.py

@@ -17,6 +17,7 @@ import unittest
 import numpy as np
 from inference_pass_test import InferencePassTest
 
+import paddle
 import paddle.fluid as fluid
 import paddle.fluid.core as core
 from paddle.fluid.core import AnalysisConfig, PassVersionChecker
@@ -27,7 +28,7 @@ class TRTGatherNdTest(InferencePassTest):
         with fluid.program_guard(self.main_program, self.startup_program):
             data = fluid.data(name="data", shape=[-1, 3, 4], dtype="float32")
             index = fluid.data(name="index", shape=[-1, 2, 2], dtype="int32")
-            gather_nd = fluid.layers.gather_nd(data, index)
+            gather_nd = paddle.gather_nd(data, index)
             out = fluid.layers.batch_norm(gather_nd, is_test=True)
 
         self.feeds = {
@@ -64,7 +65,7 @@ class TRTGatherNdFp16Test(InferencePassTest):
                 name="data", shape=[-1, 1280, 192], dtype="float32"
             )
             index = fluid.data(name="index", shape=[-1, 1028, 2], dtype="int32")
-            gather_nd = fluid.layers.gather_nd(data, index)
+            gather_nd = paddle.gather_nd(data, index)
             out = fluid.layers.batch_norm(gather_nd, is_test=True)
 
         index_data = np.zeros((1, 1028, 2), dtype='int32')

python/paddle/fluid/tests/unittests/test_dynamic_rnn_stop_gradient.py

@@ -49,7 +49,7 @@ def build_and_run_program(place, batch_size, beam_size, stop_gradient=False):
         )
         topk_coordinates = paddle.stack([batch_pos, indices], axis=2)
         topk_coordinates.stop_gradient = stop_gradient
-        score = layers.gather_nd(x, topk_coordinates)
+        score = paddle.gather_nd(x, topk_coordinates)
         layers.increment(x=step_idx, value=1.0, in_place=True)
         layers.array_write(score, i=step_idx, array=scores)
         length_cond = layers.less_than(x=step_idx, y=max_len)

python/paddle/fluid/tests/unittests/test_gather_nd_op.py

@@ -162,17 +162,17 @@ class TestGatherNdOpAPI(unittest.TestCase):
             name='x1', shape=[30, 40, 50, 60], dtype='float32'
         )
         index1 = fluid.layers.data(name='index1', shape=[2, 4], dtype='int32')
-        output1 = fluid.layers.gather_nd(x1, index1)
+        output1 = paddle.gather_nd(x1, index1)
 
     def test_case2(self):
         x2 = fluid.layers.data(name='x2', shape=[30, 40, 50], dtype='float32')
         index2 = fluid.layers.data(name='index2', shape=[2, 2], dtype='int64')
-        output2 = fluid.layers.gather_nd(x2, index2)
+        output2 = paddle.gather_nd(x2, index2)
 
     def test_case3(self):
         x3 = fluid.layers.data(name='x3', shape=[3, 4, 5], dtype='float32')
         index3 = fluid.layers.data(name='index3', shape=[2, 1], dtype='int32')
-        output3 = fluid.layers.gather_nd(x3, index3, name="gather_nd_layer")
+        output3 = paddle.gather_nd(x3, index3, name="gather_nd_layer")
 
 
 # Test Raise Index Error
@@ -186,7 +186,7 @@ class TestGatherNdOpRaise(unittest.TestCase):
                 index = fluid.layers.data(
                     name='index', shape=[2, 10], dtype='int32'
                 )
-                output = fluid.layers.gather_nd(x, index)
+                output = paddle.gather_nd(x, index)
             except Exception as e:
                 t = "Input(Index).shape[-1] should be no greater than Input(X).rank"
                 if t in str(e):