How to perform sum pooling in PyTorch

Question

How to perform sum pooling in PyTorch. Specifically, if we have input (N, C, W_in, H_in) and want output (N, C, W_out, H_out) using a particular kernel_size and stride just like nn.Maxpool2d ?

Answer 1

You could use torch.nn.AvgPool1d (or torch.nn.AvgPool2d, torch.nn.AvgPool3d) which are performing mean pooling - proportional to sum pooling. If you really want the summed values, you could multiply the averaged output by the pooling surface.

Answer 2

https://pytorch.org/docs/stable/generated/torch.nn.AvgPool2d.html#torch.nn.AvgPool2d find divisor_override.
set divisor_override=1
you'll get a sumpool

import torch
input = torch.tensor([[[1,2,3],[3,2,1],[3,4,5]]])
sumpool = torch.nn.AvgPool2d(2, stride=1, divisor_override=1)
sumpool(input)

you'll get

tensor([[[ 8,  8],
         [12, 12]]])