# Normalization Layer¶

class npdl.layers.BatchNormal(epsilon=1e-06, momentum=0.9, axis=0, beta_init='zero', gamma_init='one')[source][source]

Batch normalization layer (Ioffe and Szegedy, 2014) [1] .

Normalize the activations of the previous layer at each batch, i.e. applies a transformation that maintains the mean activation close to 0 and the activation standard deviation close to 1.

Parameters: epsilon ： small float > 0 Fuzz parameter. npdl expects epsilon >= 1e-5. axis : integer axis along which to normalize in mode 0. For instance, if your input tensor has shape (samples, channels, rows, cols), set axis to 1 to normalize per feature map (channels axis). momentum : float momentum in the computation of the exponential average of the mean and standard deviation of the data, for feature-wise normalization. beta_init : npdl.initializations.Initializer name of initialization function for shift parameter, or alternatively, npdl function to use for weights initialization. gamma_init : npdl.initializations.Initializer name of initialization function for scale parameter, or alternatively, npdl function to use for weights initialization. # Input shape Arbitrary. Use the keyword argument input_shape (tuple of integers, does not include the samples axis) when using this layer as the first layer in a model. # Output shape Same shape as input.

References

 [1] [Batch Normalization: Accelerating Deep Network Training by Reducing Internal Covariate Shift](https://arxiv.org/abs/1502.03167)
backward(pre_grad, *args, **kwargs)[source][source]

connect_to(prev_layer)[source][source]

Propagates the given input through this layer (and only this layer).

Parameters: prev_layer : previous layer The previous layer to propagate through this layer.
forward(input, *args, **kwargs)[source][source]

Calculate layer output for given input (forward propagation).

params[source]

Layer parameters.

Returns a list of numpy.array variables or expressions that parameterize the layer.

Returns: list of numpy.array variables or expressions A list of variables that parameterize the layer

Notes

For layers without any parameters, this will return an empty list.