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PReLU

keras.layers.advanced_activations.PReLU(init='zero', weights=None)

Parametric Rectified Linear Unit: f(x) = alphas * x for x < 0, f(x) = x for x >= 0, where alphas is a learned array with the same shape as x.

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 the input.

Arguments

• init: initialization function for the weights.
• weights: initial weights, as a list of a single numpy array.

References

• Delving Deep into Rectifiers: Surpassing Human-Level Performance on ImageNet Classification

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ParametricSoftplus

keras.layers.advanced_activations.ParametricSoftplus(alpha_init=0.2, beta_init=5.0, weights=None)

Parametric Softplus: alpha * log(1 + exp(beta * x))

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 the input.

Arguments

• alpha_init: float. Initial value of the alpha weights.
• beta_init: float. Initial values of the beta weights.
• weights: initial weights, as a list of 2 numpy arrays.

References

• Inferring Nonlinear Neuronal Computation Based on Physiologically Plausible Inputs

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ThresholdedReLU

keras.layers.advanced_activations.ThresholdedReLU(theta=1.0)

Thresholded Rectified Linear Unit: f(x) = x for x > theta f(x) = 0 otherwise.

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 the input.

Arguments

• theta: float >= 0. Threshold location of activation.

References

• Zero-Bias Autoencoders and the Benefits of Co-Adapting Features

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LeakyReLU

keras.layers.advanced_activations.LeakyReLU(alpha=0.3)

Special version of a Rectified Linear Unit that allows a small gradient when the unit is not active: f(x) = alpha * x for x < 0, f(x) = x for x >= 0.

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 the input.

Arguments

• alpha: float >= 0. Negative slope coefficient.

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ELU

keras.layers.advanced_activations.ELU(alpha=1.0)

Exponential Linear Unit: f(x) = alpha * (exp(x) - 1.) for x < 0, f(x) = x for x >= 0.

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 the input.

Arguments

• alpha: scale for the negative factor.

References

• Fast and Accurate Deep Network Learning by Exponential Linear Units (ELUs)

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SReLU

keras.layers.advanced_activations.SReLU(t_left_init='zero', a_left_init='glorot_uniform', t_right_init='glorot_uniform', a_right_init='one')

S-shaped Rectified Linear Unit.

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 the input.

Arguments

• t_left_init: initialization function for the left part intercept
• a_left_init: initialization function for the left part slope
• t_right_init: initialization function for the right part intercept
• a_right_init: initialization function for the right part slope

References

• Deep Learning with S-shaped Rectified Linear Activation Units