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Fractional MaxPooling is described in detail in the paper Fractional MaxPooling by Ben Graham


  output_size = NULL,
  output_ratio = NULL,
  return_indices = FALSE



the size of the window to take a max over. Can be a single number k (for a square kernel of k x k x k) or a tuple (kt x kh x kw)


the target output size of the image of the form oT x oH x oW. Can be a tuple (oT, oH, oW) or a single number oH for a square image oH x oH x oH


If one wants to have an output size as a ratio of the input size, this option can be given. This has to be a number or tuple in the range (0, 1)


if TRUE, will return the indices along with the outputs. Useful to pass to nn_max_unpool3d(). Default: FALSE


The max-pooling operation is applied in \(kTxkHxkW\) regions by a stochastic step size determined by the target output size. The number of output features is equal to the number of input planes.


if (torch_is_installed()) {
# pool of cubic window of size=3, and target output size 13x12x11
m <- nn_fractional_max_pool3d(3, output_size = c(13, 12, 11))
# pool of cubic window and target output size being half of input size
m <- nn_fractional_max_pool3d(3, output_ratio = c(0.5, 0.5, 0.5))
input <- torch_randn(20, 16, 50, 32, 16)
output <- m(input)