Numpy实现ZeroPadding2D

秒速五厘米 2022-09-11 11:10 167阅读 0赞

class ConstantPadding2D(Layer):
        """Adds rows and columns of constant values to the input. Expects the input to be of shape (batch_size, channels, height, width) Parameters: ----------- padding: tuple The amount of padding along the height and width dimension of the input. If (pad_h, pad_w) the same symmetric padding is applied along height and width dimension. If ((pad_h0, pad_h1), (pad_w0, pad_w1)) the specified padding is added to beginning and end of the height and width dimension. padding_value: int or tuple The value the is added as padding. """
        def __init__(self, padding, padding_value=0):
            self.padding = padding
            self.trainable = True
            if not isinstance(padding[0], tuple):
                self.padding = ((padding[0], padding[0]), padding[1])
            if not isinstance(padding[1], tuple):
                self.padding = (self.padding[0], (padding[1], padding[1]))
            self.padding_value = padding_value
    
        def forward_pass(self, X, training=True):
            output = np.pad(X,
                pad_width=((0,0), (0,0), self.padding[0], self.padding[1]),
                mode="constant",
                constant_values=self.padding_value)
            return output
    
        def backward_pass(self, accum_grad):
            pad_top, pad_left = self.padding[0][0], self.padding[1][0]
            height, width = self.input_shape[1], self.input_shape[2]
            accum_grad = accum_grad[:, :, pad_top:pad_top+height, pad_left:pad_left+width]
            return accum_grad
    
        def output_shape(self):
            new_height = self.input_shape[1] + np.sum(self.padding[0])
            new_width = self.input_shape[2] + np.sum(self.padding[1])
            return (self.input_shape[0], new_height, new_width)
    
    
    class ZeroPadding2D(ConstantPadding2D):
        """Adds rows and columns of zero values to the input. Expects the input to be of shape (batch_size, channels, height, width) Parameters: ----------- padding: tuple The amount of padding along the height and width dimension of the input. If (pad_h, pad_w) the same symmetric padding is applied along height and width dimension. If ((pad_h0, pad_h1), (pad_w0, pad_w1)) the specified padding is added to beginning and end of the height and width dimension. """
        def __init__(self, padding):
            self.padding = padding
            if isinstance(padding[0], int):
                self.padding = ((padding[0], padding[0]), padding[1])
            if isinstance(padding[1], int):
                self.padding = (self.padding[0], (padding[1], padding[1]))
            self.padding_value = 0