Source code for monai.networks.blocks.downsample

# Copyright 2020 - 2021 MONAI Consortium
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
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from typing import Optional, Sequence, Union

import torch
import torch.nn as nn

from monai.networks.layers.factories import Pool
from monai.utils import ensure_tuple_rep

[docs]class MaxAvgPool(nn.Module): """ Downsample with both maxpooling and avgpooling, double the channel size by concatenating the downsampled feature maps. """ def __init__( self, spatial_dims: int, kernel_size: Union[Sequence[int], int], stride: Optional[Union[Sequence[int], int]] = None, padding: Union[Sequence[int], int] = 0, ceil_mode: bool = False, ) -> None: """ Args: spatial_dims: number of spatial dimensions of the input image. kernel_size: the kernel size of both pooling operations. stride: the stride of the window. Default value is `kernel_size`. padding: implicit zero padding to be added to both pooling operations. ceil_mode: when True, will use ceil instead of floor to compute the output shape. """ super().__init__() _params = { "kernel_size": ensure_tuple_rep(kernel_size, spatial_dims), "stride": None if stride is None else ensure_tuple_rep(stride, spatial_dims), "padding": ensure_tuple_rep(padding, spatial_dims), "ceil_mode": ceil_mode, } self.max_pool = Pool[Pool.MAX, spatial_dims](**_params) self.avg_pool = Pool[Pool.AVG, spatial_dims](**_params)
[docs] def forward(self, x: torch.Tensor) -> torch.Tensor: """ Args: x: Tensor in shape (batch, channel, spatial_1[, spatial_2, ...]). Returns: Tensor in shape (batch, 2*channel, spatial_1[, spatial_2, ...]). """ x_d =[self.max_pool(x), self.avg_pool(x)], dim=1) return x_d