Class: DNN::Layers::MaxPool2D

Inherits:
Pool2D show all
Defined in:
lib/dnn/core/cnn_layers.rb

Instance Attribute Summary

Attributes inherited from Pool2D

#padding, #pool_size, #strides

Attributes inherited from Layer

#input_shape, #learning_phase

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Pool2D

#build, #initialize, #output_shape, #to_hash

Methods inherited from Layer

#build, #built?, #initialize, #output_shape, #to_hash

Constructor Details

This class inherits a constructor from DNN::Layers::Pool2D

Class Method Details

.from_hash(hash) ⇒ Object 



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# File 'lib/dnn/core/cnn_layers.rb', line 357

def self.from_hash(hash)
  Pool2D.from_hash(self, hash)
end

Instance Method Details

#backward(dy) ⇒ Object 



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# File 'lib/dnn/core/cnn_layers.rb', line 371

def backward(dy)
  dmax = Xumo::SFloat.zeros(dy.size * @pool_size.reduce(:*))
  dmax[@max_index] = dy.flatten
  dcol = dmax.reshape(dy.shape[0..2].reduce(:*), @pool_size.reduce(:*) * dy.shape[3])
  dx = col2im(dcol, @x_shape, *@out_size, *@pool_size, @strides)
  @padding ? zero_padding_bwd(dx, @pad_size) : dx
end

#forward(x) ⇒ Object 



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# File 'lib/dnn/core/cnn_layers.rb', line 361

def forward(x)
  x = zero_padding(x, @pad_size) if @padding
  @x_shape = x.shape
  col = im2col(x, *@out_size, *@pool_size, @strides)
  col = col.reshape(x.shape[0] * @out_size.reduce(:*), @pool_size.reduce(:*), x.shape[3]).transpose(0, 2, 1)
           .reshape(x.shape[0] * @out_size.reduce(:*) * x.shape[3], @pool_size.reduce(:*))
  @max_index = col.max_index(1)
  col.max(1).reshape(x.shape[0], *@out_size, x.shape[3])
end