# Copyright 2022 Huawei Technologies Co., Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
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# ============================================================================
"""Maximum Pooling Layer"""
# pylint: disable=unused-import
import mindspore
from mindspore_gl import BatchedGraph
from .. import GNNCell
[文档]class MaxPooling(GNNCell):
r"""
Apply maximum pooling to the nodes in the batched graph.
.. math::
r^{(i)} = \max_{k=1}^{N_i}\left( x^{(i)}_k \right)
Inputs:
- **x** (Tensor) - The input node features to be updated. The shape is :math:`(N, D)`
where :math:`N` is the number of nodes, and :math:`D` is the feature size of nodes.
- **g** (BatchedGraph) - The input graph.
Outputs:
- **x** (Tensor) - The output representation for graphs. The shape is :math:`(2, D_{out})`
where :math:`D_{out}` is the feature size of nodes
Supported Platforms:
``Ascend`` ``GPU``
Examples:
>>> import numpy as np
>>> import mindspore as ms
>>> from mindspore_gl.nn import MaxPooling
>>> from mindspore_gl import BatchedGraphField
>>> n_nodes = 7
>>> n_edges = 8
>>> src_idx = ms.Tensor([0, 2, 2, 3, 4, 5, 5, 6], ms.int32)
>>> dst_idx = ms.Tensor([1, 0, 1, 5, 3, 4, 6, 4], ms.int32)
>>> ver_subgraph_idx = ms.Tensor([0, 0, 0, 1, 1, 1, 1], ms.int32)
>>> edge_subgraph_idx = ms.Tensor([0, 0, 0, 1, 1, 1, 1, 1], ms.int32)
>>> graph_mask = ms.Tensor([1, 1], ms.int32)
>>> batched_graph_field = BatchedGraphField(src_idx, dst_idx, n_nodes, n_edges, ver_subgraph_idx,
... edge_subgraph_idx, graph_mask)
>>> node_feat = np.random.random((n_nodes, 4))
>>> node_feat = ms.Tensor(node_feat, ms.float32)
>>> net = MaxPooling()
>>> ret = net(node_feat, *batched_graph_field.get_batched_graph())
>>> print(ret.shape)
(2, 4)
"""
# pylint: disable=arguments-differ
def construct(self, x, g: BatchedGraph):
"""
Construct function for MaxPooling.
"""
return g.max_nodes(x)