Encoders & Decoders

struct Encoder{E<:Union{Flux.Chain,Flux.Dense}} <: AbstractDeterministicEncoder

Default encoder function for deterministic autoencoders. The encoder network is used to map the input data directly into the latent space representation.

Fields

• encoder::Union{Flux.Chain,Flux.Dense}: The primary neural network used to process input data and map it into a latent space representation.

Example

enc = Encoder(Flux.Chain(Dense(784, 400, relu), Dense(400, 20)))

(encoder::Encoder)(x)

Forward propagate the input x through the Encoder to obtain the encoded representation in the latent space.

Arguments

• x::Array: Input data to be encoded.

Returns

• z: Encoded representation of the input data in the latent space.

Description

This method allows for a direct call on an instance of Encoder with the input data x. It runs the input through the encoder network and outputs the encoded representation in the latent space.

Example

enc = Encoder(...)
z = enc(some_input)

Note

Ensure that the input x matches the expected dimensionality of the encoder's input layer.

struct JointGaussianEncoder <: AbstractGaussianLinearEncoder

Encoder function for variational autoencoders where the same encoder network is used to map to the latent space mean µ and standard deviation σ.

Fields

• encoder::Flux.Chain: The primary neural network used to process input data and map it into a latent space representation.
• µ::Flux.Dense: A dense layer mapping from the output of the encoder to the mean of the latent space.
• σ::Flux.Dense: A dense layer mapping from the output of the encoder to the standard deviation of the latent space.

Example

enc = JointGaussianEncoder(
    Flux.Chain(Dense(784, 400, relu)), Flux.Dense(400, 20), Flux.Dense(400, 20)
)

    (encoder::JointGaussianEncoder)(x::AbstractArray)

Forward propagate the input x through the JointGaussianEncoder to obtain the mean (µ) and standard deviation (σ) of the latent space.

Arguments

• x::AbstractArray: Input data to be encoded.

Returns

• A NamedTuple (µ=µ, σ=σ,) where:
  • µ: Mean of the latent space after passing the input through the encoder and subsequently through the µ layer.
  • σ: Standard deviation of the latent space after passing the input through the encoder and subsequently through the σ layer.

Description

This method allows for a direct call on an instance of JointGaussianEncoder with the input data x. It first runs the input through the encoder network, then maps the output of the last encoder layer to both the mean and standard deviation of the latent space.

Example

je = JointGaussianEncoder(...)
µ, σ = je(some_input)

Note

Ensure that the input x matches the expected dimensionality of the encoder's input layer.

struct JointGaussianLogEncoder <: AbstractGaussianLogEncoder

Default encoder function for variational autoencoders where the same encoder network is used to map to the latent space mean µ and log standard deviation logσ.

Fields

• encoder::Flux.Chain: The primary neural network used to process input data and map it into a latent space representation.
• µ::Union{Flux.Dense,Flux.Chain}: A dense layer or a chain of layers mapping from the output of the encoder to the mean of the latent space.
• logσ::Union{Flux.Dense,Flux.Chain}: A dense layer or a chain of layers mapping from the output of the encoder to the log standard deviation of the latent space.

Example

enc = JointGaussianLogEncoder(
        Flux.Chain(Dense(784, 400, relu)), Flux.Dense(400, 20), Flux.Dense(400, 20)
)

    (encoder::JointGaussianLogEncoder)(x)

This method forward propagates the input x through the JointGaussianLogEncoder to compute the mean (mu) and log standard deviation (logσ) of the latent space.

Arguments

• x::Array{Float32}: The input data to be encoded.

Returns

• A NamedTuple (µ=µ, logσ=logσ,) where:
  • µ: The mean of the latent space. This is computed by passing the input through the encoder and subsequently through the µ layer.
  • logσ: The log standard deviation of the latent space. This is computed by passing the input through the encoder and subsequently through the logσ layer.

Description

This method allows for a direct call on an instance of JointGaussianLogEncoder with the input data x. It first processes the input through the encoder network, then maps the output of the last encoder layer to both the mean and log standard deviation of the latent space.

Example

je = JointGaussianLogEncoder(...)
mu, logσ = je(some_input)

Note

Ensure that the input x matches the expected dimensionality of the encoder's input layer.

struct Decoder{D<:Flux.Chain} <: AbstractDeterministicDecoder

Default decoder function for deterministic autoencoders. The decoder network is used to map the latent space representation directly back to the original data space.

Fields

• decoder::Flux.Chain: The primary neural network used to process the latent space representation and map it back to the data space.

Example

dec = Decoder(Flux.Chain(Dense(20, 400, relu), Dense(400, 784)))

(decoder::Decoder)(z::AbstractArray)

Forward propagate the encoded representation z through the Decoder to obtain the reconstructed input data.

Arguments

• z::AbstractArray: Encoded representation in the latent space.

Returns

• x_reconstructed: Reconstructed version of the original input data after decoding from the latent space.

Description

This method allows for a direct call on an instance of Decoder with the encoded data z. It runs the encoded representation through the decoder network and outputs the reconstructed version of the original input data.

Example

julia dec = Decoder(...) x_reconstructed = dec(encoded_representation)`

Note

Ensure that the input z matches the expected dimensionality of the decoder's input layer.

    BernoulliDecoder{D<:Flux.Chain} <: AbstractVariationalDecoder

A decoder structure for variational autoencoders (VAEs) that models the output data as a Bernoulli distribution. This is typically used when the outputs of the decoder are probabilities.

Fields

• decoder::Flux.Chain: The primary neural network used to process the latent space and map it to the output (or reconstructed) space.

Description

BernoulliDecoder represents a VAE decoder that models the output data as a Bernoulli distribution. It's commonly used when the outputs of the decoder are probabilities, such as in a binary classification task or when modeling binary data. Unlike a Gaussian decoder, there's no need for separate paths or operations on the mean or log standard deviation.

Note

Ensure the last layer of the decoder outputs a value between 0 and 1, as this is required for a Bernoulli distribution.

    (decoder::BernoulliDecoder)(z::AbstractArray)

Maps the given latent representation z through the BernoulliDecoder network to reconstruct the original input.

Arguments

• z::AbstractArray: The latent space representation to be decoded. This can be a vector or a matrix, where each column represents a separate sample from the latent space of a VAE.

Returns

• A NamedTuple (p=p,) where p is an array representing the output of the decoder, which should resemble the original input to the VAE (post encoding and sampling from the latent space).

Description

This function processes the latent space representation z using the neural network defined in the BernoulliDecoder struct. The aim is to decode or reconstruct the original input from this representation.

Note

Ensure that the latent space representation z matches the expected input dimensionality for the BernoulliDecoder.

CategoricalDecoder{D<:Flux.Chain} <: AbstractVariationalDecoder

A decoder structure for variational autoencoders (VAEs) that models the output data as a categorical distribution. This is typically used when the outputs of the decoder are categorical variables encoded as one-hot vectors.

Fields

• decoder::Flux.Chain: The primary neural network used to process the latent space and map it to the output (or reconstructed) space.

Description

CategoricalDecoder represents a VAE decoder that models the output data as a categorical distribution. It's commonly used when the outputs of the decoder are categorical variables, such as in a multi-class one-hot encoded vectors. Unlike a Gaussian decoder, there's no need for separate paths or operations on the mean or log standard deviation.

Note

Ensure the last layer of the decoder outputs a probability distribution over the categories, as this is required for a categorical distribution. This can be done using a softmax activation function, for example.

(decoder::CategoricalDecoder)(z::AbstractArray)

Maps the given latent representation z through the CategoricalDecoder network to reconstruct the original input.

Arguments

• z::AbstractArray: The latent space representation to be decoded. This can be a vector or a matrix, where each column represents a separate sample from the latent space of a VAE.

Returns

• A NamedTuple (p=p,) where p is an array representing the output of the decoder, which should resemble the original input to the VAE (post encoding and sampling from the latent space).

Description

This function processes the latent space representation z using the neural network defined in the CategoricalDecoder struct. The aim is to decode or reconstruct the original input from this representation.

Note

Ensure that the latent space representation z matches the expected input dimensionality for the CategoricalDecoder.

SimpleGaussianDecoder{D} <: AbstractGaussianDecoder

A straightforward decoder structure for variational autoencoders (VAEs) that contains only a single decoder network.

Fields

• decoder::Flux.Chain: The primary neural network used to process the latent space and map it to the output (or reconstructed) space.

Description

SimpleGaussianDecoder represents a basic VAE decoder without explicit components for the latent space's mean (µ) or log standard deviation (logσ). It's commonly used when the VAE's latent space distribution is implicitly defined, and there's no need for separate paths or operations on the mean or log standard deviation.

(decoder::SimpleGaussianDecoder)(z::AbstractVecOrMat)

Maps the given latent representation z through the SimpleGaussianDecoder network to reconstruct the original input.

Arguments

• z::AbstractArray: The latent space representation to be decoded. This can be a vector or a matrix, where each column represents a separate sample from the latent space of a VAE.

Returns

• A NamedTuple (µ=µ,) where µ is an array representing the output of the decoder, which should resemble the original input to the VAE (post encoding and sampling from the latent space).

Description

This function processes the latent space representation z using the neural network defined in the SimpleGaussianDecoder struct. The aim is to decode or reconstruct the original input from this representation.

Example

decoder = SimpleGaussianDecoder(...)
z = ... # some latent space representation
output = decoder(z)

Note

Ensure that the latent space representation z matches the expected input dimensionality for the SimpleGaussianDecoder.

JointGaussianDecoder{D<:Flux.Chain,L<:Flux.Dense} <: AbstractGaussianLinearDecoder

An extended decoder structure for VAEs that incorporates separate layers for mapping from the latent space to both its mean (µ) and standard deviation (σ).

Fields

• decoder::Flux.Chain: The primary neural network used to process the latent space before determining its mean and log standard deviation.
• µ::Flux.Dense: A dense layer that maps from the output of the decoder to the mean of the latent space.
• σ::Flux.Dense: A dense layer that maps from the output of the decoder to the standard deviation of the latent space.

Description

JointGaussianDecoder is tailored for VAE architectures where the same decoder network is used initially, and then splits into two separate paths for determining both the mean and standard deviation of the latent space.

    (decoder::JointGaussianDecoder)(z::AbstractArray)

Maps the given latent representation z through the JointGaussianDecoder network to produce both the mean (µ) and standard deviation (σ).

Arguments

• z::AbstractArray: The latent space representation to be decoded. If array, the last dimension contains each of the latent space representations to be decoded.

Returns

• A NamedTuple (µ=µ, σ=σ,) where:
  • µ::AbstractArray: The mean representation obtained from the decoder.
  • σ::AbstractArray: The standard deviation representation obtained from the decoder.

Description

This function processes the latent space representation z using the primary neural network of the JointGaussianDecoder struct. It then separately maps the output of this network to the mean and standard deviation using the µ and σ dense layers, respectively.

Example

decoder = JointGaussianDecoder(...)
z = ... # some latent space representation
output = decoder(z)

Note

Ensure that the latent space representation z matches the expected input dimensionality for the JointGaussianDecoder.

JointGaussianLogDecoder{D<:Flux.Chain,L<:Flux.Dense} <: AbstractGaussianLogDecoder

An extended decoder structure for VAEs that incorporates separate layers for mapping from the latent space to both its mean (µ) and log standard deviation (logσ).

Fields

• decoder::Flux.Chain: The primary neural network used to process the latent space before determining its mean and log standard deviation.
• µ::Flux.Dense: A dense layer that maps from the output of the decoder to the mean of the latent space.
• logσ::Flux.Dense: A dense layer that maps from the output of the decoder to the log standard deviation of the latent space.

Description

JointGaussianLogDecoder is tailored for VAE architectures where the same decoder network is used initially, and then splits into two separate paths for determining both the mean and log standard deviation of the latent space.

    (decoder::JointGaussianLogDecoder)(z::AbstractArray)

Maps the given latent representation z through the JointGaussianLogDecoder network to produce both the mean (µ) and log standard deviation (logσ).

Arguments

• z::AbstractArray: The latent space representation to be decoded. If array, the last dimension contains each of the latent space representations.

Returns

• A NamedTuple (µ=µ, logσ=logσ,) where:
  • µ::Array: The mean representation obtained from the decoder.
  • logσ::Array: The log standard deviation representation obtained from the decoder.

Description

This function processes the latent space representation z using the primary neural network of the JointGaussianLogDecoder struct. It then separately maps the output of this network to the mean and log standard deviation using the µ and logσ dense layers, respectively.

Example

decoder = JointGaussianLogDecoder(...)
z = ... # some latent space representation
output = decoder(z)

Note

Ensure that the latent space representation z matches the expected input dimensionality for the JointGaussianLogDecoder.

SplitGaussianDecoder{D<:Flux.Chain} <: AbstractGaussianLinearDecoder

A specialized decoder structure for VAEs that uses distinct neural networks for determining the mean (µ) and standard deviation (logσ) of the latent space.

Fields

• decoder_µ::Flux.Chain: A neural network dedicated to processing the latent space and mapping it to its mean.
• decoder_σ::Flux.Chain: A neural network dedicated to processing the latent space and mapping it to its standard deviation.

Description

SplitGaussianDecoder is designed for VAE architectures where separate decoder networks are preferred for computing the mean and log standard deviation, ensuring that each has its own distinct set of parameters and transformation logic.

    (decoder::SplitGaussianDecoder)(z::AbstractArray)

Maps the given latent representation z through the separate networks of the SplitGaussianDecoder to produce both the mean (µ) and standard deviation (σ).

Arguments

• z::AbstractArray: The latent space representation to be decoded. If array, the last dimension contains each of the latent space representations to be decoded.

Returns

• A NamedTuple (µ=µ, σ=σ,) where:
  • µ::AbstractArray: The mean representation obtained using the dedicated decoder_µ network.
  • σ::AbstractArray: The standard deviation representation obtained using the dedicated decoder_σ network.

Description

This function processes the latent space representation z through two distinct neural networks within the SplitGaussianDecoder struct. The decoder_µ network is used to produce the mean representation, while the decoder_σ network is utilized for the standard deviation.

Example

decoder = SplitGaussianDecoder(...)
z = ... # some latent space representation
output = decoder(z)

Note

Ensure that the latent space representation z matches the expected input dimensionality for both networks in the SplitGaussianDecoder.

SplitGaussianLogDecoder{D<:Flux.Chain} <: AbstractGaussianLogDecoder

A specialized decoder structure for VAEs that uses distinct neural networks for determining the mean (µ) and log standard deviation (logσ) of the latent space.

Fields

• decoder_µ::Flux.Chain: A neural network dedicated to processing the latent space and mapping it to its mean.
• decoder_logσ::Flux.Chain: A neural network dedicated to processing the latent space and mapping it to its log standard deviation.

Description

SplitGaussianLogDecoder is designed for VAE architectures where separate decoder networks are preferred for computing the mean and log standard deviation, ensuring that each has its own distinct set of parameters and transformation logic.

    (decoder::SplitGaussianLogDecoder)(z::AbstractArray)

Maps the given latent representation z through the separate networks of the SplitGaussianLogDecoder to produce both the mean (µ) and log standard deviation (logσ).

Arguments

• z::AbstractArray: The latent space representation to be decoded. If array, the last dimension contains each of the latent space representations to be decoded.

Returns

• A NamedTuple (µ=µ, logσ=logσ,) where:
  • µ::AbstractArray: The mean representation obtained using the dedicated decoder_µ network.
  • logσ::AbstractArray: The log standard deviation representation obtained using the dedicated decoder_logσ network.

Description

This function processes the latent space representation z through two distinct neural networks within the SplitGaussianLogDecoder struct. The decoder_µ network is used to produce the mean representation, while the decoder_logσ network is utilized for the log standard deviation.

Example

decoder = SplitGaussianLogDecoder(...)
z = ... # some latent space representation
output = decoder(z))

Note

Ensure that the latent space representation z matches the expected input dimensionality for both networks in the SplitGaussianLogDecoder.

Encoder(n_input, n_latent, latent_activation, encoder_neurons, 
        encoder_activation; init=Flux.glorot_uniform)

Construct and initialize an Encoder struct that defines an encoder network for a deterministic autoencoder.

Arguments

• n_input::Int: The dimensionality of the input data.
• n_latent::Int: The dimensionality of the latent space.
• encoder_neurons::Vector{<:Int}: A vector specifying the number of neurons in each layer of the encoder network.
• encoder_activation::Vector{<:Function}: Activation functions corresponding to each layer in the encoder_neurons.
• latent_activation::Function: Activation function for the latent space layer.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: The initialization function used for the neural network weights.

Returns

• An Encoder struct initialized based on the provided arguments.

Examples

julia encoder = Encoder(784, 20, tanh, [400], [relu])`

Notes

The length of encoderneurons should match the length of encoderactivation, ensuring that each layer in the encoder has a corresponding activation function.

JointGaussianLogEncoder(n_input, n_latent, encoder_neurons, encoder_activation, 
             latent_activation; init=Flux.glorot_uniform)

Construct and initialize a JointGaussianLogEncoder struct that defines an encoder network for a variational autoencoder.

Arguments

• n_input::Int: The dimensionality of the input data.
• n_latent::Int: The dimensionality of the latent space.
• encoder_neurons::Vector{<:Int}: A vector specifying the number of neurons in each layer of the encoder network.
• encoder_activation::Vector{<:Function}: Activation functions corresponding to each layer in the encoder_neurons.
• latent_activation::Function: Activation function for the latent space layers (both µ and logσ).

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: The initialization function used for the neural network weights.

Returns

• A JointGaussianLogEncoder struct initialized based on the provided arguments.

Examples

encoder = JointGaussianLogEncoder(784, 20, [400], [relu], tanh)

Notes

The length of encoderneurons should match the length of encoderactivation, ensuring that each layer in the encoder has a corresponding activation function.

JointGaussianLogEncoder(n_input, n_latent, encoder_neurons, encoder_activation, 
             latent_activation; init=Flux.glorot_uniform)

Construct and initialize a JointGaussianLogEncoder struct that defines an encoder network for a variational autoencoder.

Arguments

• n_input::Int: The dimensionality of the input data.
• n_latent::Int: The dimensionality of the latent space.
• encoder_neurons::Vector{<:Int}: A vector specifying the number of neurons in each layer of the encoder network.
• encoder_activation::Vector{<:Function}: Activation functions corresponding to each layer in the encoder_neurons.
• latent_activation::Vector{<:Function}: Activation functions for the latent space layers (both µ and logσ).

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: The initialization function used for the neural network weights.

Returns

• A JointGaussianLogEncoder struct initialized based on the provided arguments.

Examples

encoder = JointGaussianLogEncoder(784, 20, [400], [relu], tanh)

Notes

The length of encoderneurons should match the length of encoderactivation, ensuring that each layer in the encoder has a corresponding activation function.

JointGaussianEncoder(n_input, n_latent, encoder_neurons, encoder_activation, 
             latent_activation; init=Flux.glorot_uniform)

Construct and initialize a JointGaussianLogEncoder struct that defines an encoder network for a variational autoencoder.

Arguments

• n_input::Int: The dimensionality of the input data.
• n_latent::Int: The dimensionality of the latent space.
• encoder_neurons::Vector{<:Int}: A vector specifying the number of neurons in each layer of the encoder network.
• encoder_activation::Vector{<:Function}: Activation functions corresponding to each layer in the encoder_neurons.
• latent_activation::Vector{<:Function}: Activation function for the latent space layers. This vector must contain the activation for both µ and logσ.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: The initialization function used for the neural network weights.

Returns

• A JointGaussianEncoder struct initialized based on the provided arguments.

Examples

encoder = JointGaussianEncoder(784, 20, [400], [relu], [tanh, softplus])

Notes

The length of encoderneurons should match the length of encoderactivation, ensuring that each layer in the encoder has a corresponding activation function.

Decoder(n_input, n_latent, decoder_neurons, decoder_activation, 
        output_activation; init=Flux.glorot_uniform)

Construct and initialize a Decoder struct that defines a decoder network for a deterministic autoencoder.

Arguments

• n_input::Int: The dimensionality of the output data (which typically matches the input data dimensionality of the autoencoder).
• n_latent::Int: The dimensionality of the latent space.
• decoder_neurons::Vector{<:Int}: A vector specifying the number of neurons in each layer of the decoder network.
• decoder_activation::Vector{<:Function}: Activation functions corresponding to each layer in the decoder_neurons.
• output_activation::Function: Activation function for the final output layer.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: The initialization function used for the neural network weights.

Returns

• A Decoder struct initialized based on the provided arguments.

Examples

decoder = Decoder(784, 20, sigmoid, [400], [relu])

Notes

The length of decoderneurons should match the length of decoderactivation, ensuring that each layer in the decoder has a corresponding activation function.

SimpleGaussianDecoder(
    n_input, n_latent, decoder_neurons, 
    decoder_activation, output_activation; 
    init=Flux.glorot_uniform
)

Constructs and initializes a SimpleGaussianDecoder object designed for variational autoencoders (VAEs). This function sets up a straightforward decoder network that maps from a latent space to an output space.

Arguments

• n_input::Int: Dimensionality of the output data (or the data to be reconstructed).
• n_latent::Int: Dimensionality of the latent space.
• decoder_neurons::Vector{<:Int}: Vector of layer sizes for the decoder network, not including the input latent layer and the final output layer.
• decoder_activation::Vector{<:Function}: Activation functions for each decoder layer, not including the final output layer.
• output_activation::Function: Activation function for the final output layer.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: Initialization function for the network parameters.

Returns

A SimpleGaussianDecoder object with the specified architecture and initialized weights.

Description

This function constructs a SimpleGaussianDecoder object, setting up its decoder network based on the provided specifications. The architecture begins with a dense layer mapping from the latent space, goes through a sequence of middle layers if specified, and finally maps to the output space.

The function ensures that there are appropriate activation functions provided for each layer in the decoder_neurons and checks for potential mismatches in length.

Example

n_input = 28*28
n_latent = 64
decoder_neurons = [128, 256]
decoder_activation = [relu, relu]
output_activation = sigmoid
decoder = SimpleGaussianDecoder(
    n_input, n_latent, decoder_neurons, decoder_activation, output_activation
)

Note

Ensure that the lengths of decoderneurons and decoderactivation match, excluding the output layer.

JointGaussianLogDecoder(n_input, n_latent, decoder_neurons, decoder_activation, 
            latent_activation; init=Flux.glorot_uniform)

Constructs and initializes a JointGaussianLogDecoder object for variational autoencoders (VAEs). This function sets up a decoder network that first processes the latent space and then maps it separately to both its mean (µ) and log standard deviation (logσ).

Arguments

• n_input::Int: Dimensionality of the output data (or the data to be reconstructed).
• n_latent::Int: Dimensionality of the latent space.
• decoder_neurons::Vector{<:Int}: Vector of layer sizes for the primary decoder network, not including the input latent layer.
• decoder_activation::Vector{<:Function}: Activation functions for each primary decoder layer.
• output_activation::Function: Activation function for the mean (µ) and log standard deviation (logσ) layers.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: Initialization function for the network parameters.

Returns

A JointGaussianLogDecoder object with the specified architecture and initialized weights.

Description

This function constructs a JointGaussianLogDecoder object, setting up its primary decoder network based on the provided specifications. The architecture begins with a dense layer mapping from the latent space and goes through a sequence of middle layers if specified. After processing the latent space through the primary decoder, it then maps separately to both its mean (µ) and log standard deviation (logσ).

Example

n_input = 28*28
n_latent = 64
decoder_neurons = [128, 256]
decoder_activation = [relu, relu]
output_activation = tanh
decoder = JointGaussianLogDecoder(
    n_input, n_latent, decoder_neurons, decoder_activation, output_activation
)

Note

Ensure that the lengths of decoderneurons and decoderactivation match.

JointGaussianLogDecoder(n_input, n_latent, decoder_neurons, decoder_activation, 
            latent_activation; init=Flux.glorot_uniform)

Constructs and initializes a JointGaussianLogDecoder object for variational autoencoders (VAEs). This function sets up a decoder network that first processes the latent space and then maps it separately to both its mean (µ) and log standard deviation (logσ).

Arguments

• n_input::Int: Dimensionality of the output data (or the data to be reconstructed).
• n_latent::Int: Dimensionality of the latent space.
• decoder_neurons::Vector{<:Int}: Vector of layer sizes for the primary decoder network, not including the input latent layer.
• decoder_activation::Vector{<:Function}: Activation functions for each primary decoder layer.
• output_activation::Vector{<:Function}: Activation functions for the mean (µ) and log standard deviation (logσ) layers.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: Initialization function for the network parameters.

Returns

A JointGaussianLogDecoder object with the specified architecture and initialized weights.

Description

This function constructs a JointGaussianLogDecoder object, setting up its primary decoder network based on the provided specifications. The architecture begins with a dense layer mapping from the latent space and goes through a sequence of middle layers if specified. After processing the latent space through the primary decoder, it then maps separately to both its mean (µ) and log standard deviation (logσ).

Example

n_input = 28*28
n_latent = 64
decoder_neurons = [128, 256]
decoder_activation = [relu, relu]
output_activation = [tanh, identity]
decoder = JointGaussianLogDecoder(
    n_input, n_latent, decoder_neurons, decoder_activation, latent_activation
)

Note

Ensure that the lengths of decoderneurons and decoderactivation match.

JointGaussianDecoder(n_input, n_latent, decoder_neurons, decoder_activation, 
            latent_activation; init=Flux.glorot_uniform)

Constructs and initializes a JointGaussianLogDecoder object for variational autoencoders (VAEs). This function sets up a decoder network that first processes the latent space and then maps it separately to both its mean (µ) and log standard deviation (logσ).

Arguments

• n_input::Int: Dimensionality of the output data (or the data to be reconstructed).
• n_latent::Int: Dimensionality of the latent space.
• decoder_neurons::Vector{<:Int}: Vector of layer sizes for the primary decoder network, not including the input latent layer.
• decoder_activation::Vector{<:Function}: Activation functions for each primary decoder layer.
• output_activation::Function: Activation function for the mean (µ) and log standard deviation (logσ) layers.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: Initialization function for the network parameters.

Returns

A JointGaussianDecoder object with the specified architecture and initialized weights.

Description

This function constructs a JointGaussianDecoder object, setting up its primary decoder network based on the provided specifications. The architecture begins with a dense layer mapping from the latent space and goes through a sequence of middle layers if specified. After processing the latent space through the primary decoder, it then maps separately to both its mean (µ) and standard deviation (σ).

Example

n_input = 28*28
n_latent = 64
decoder_neurons = [128, 256]
decoder_activation = [relu, relu]
output_activation = tanh
decoder = JointGaussianDecoder(
    n_input, n_latent, decoder_neurons, decoder_activation, output_activation
)

Note

Ensure that the lengths of decoderneurons and decoderactivation match.

JointGaussianDecoder(n_input, n_latent, decoder_neurons, decoder_activation, 
            latent_activation; init=Flux.glorot_uniform)

Constructs and initializes a JointGaussianDecoder object for variational autoencoders (VAEs). This function sets up a decoder network that first processes the latent space and then maps it separately to both its mean (µ) and standard deviation (σ).

Arguments

• n_input::Int: Dimensionality of the output data (or the data to be reconstructed).
• n_latent::Int: Dimensionality of the latent space.
• decoder_neurons::Vector{<:Int}: Vector of layer sizes for the primary decoder network, not including the input latent layer.
• decoder_activation::Vector{<:Function}: Activation functions for each primary decoder layer.
• output_activation::Function: Activation function for the mean (µ) and standard deviation (σ) layers.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: Initialization function for the network parameters.

Returns

A JointGaussianDecoder object with the specified architecture and initialized weights.

Description

This function constructs a JointGaussianDecoder object, setting up its primary decoder network based on the provided specifications. The architecture begins with a dense layer mapping from the latent space and goes through a sequence of middle layers if specified. After processing the latent space through the primary decoder, it then maps separately to both its mean (µ) and standard deviation (σ).

Example

n_input = 28*28
n_latent = 64
decoder_neurons = [128, 256]
decoder_activation = [relu, relu]
latent_activation = [tanh, softplus]
decoder = JointGaussianDecoder(
    n_input, n_latent, decoder_neurons, decoder_activation, latent_activation
)

Note

Ensure that the lengths of decoderneurons and decoderactivation match.

SplitGaussianLogDecoder(n_input, n_latent, µ_neurons, µ_activation, logσ_neurons, 
            logσ_activation; init=Flux.glorot_uniform)

Constructs and initializes a SplitGaussianLogDecoder object for variational autoencoders (VAEs). This function sets up two distinct decoder networks, one dedicated for determining the mean (µ) and the other for the log standard deviation (logσ) of the latent space.

Arguments

• n_input::Int: Dimensionality of the output data (or the data to be reconstructed).
• n_latent::Int: Dimensionality of the latent space.
• µ_neurons::Vector{<:Int}: Vector of layer sizes for the µ decoder network, not including the input latent layer.
• µ_activation::Vector{<:Function}: Activation functions for each µ decoder layer.
• logσ_neurons::Vector{<:Int}: Vector of layer sizes for the logσ decoder network, not including the input latent layer.
• logσ_activation::Vector{<:Function}: Activation functions for each logσ decoder layer.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: Initialization function for the network parameters.

Returns

A SplitGaussianLogDecoder object with two distinct networks initialized with the specified architectures and weights.

Description

This function constructs a SplitGaussianLogDecoder object, setting up two separate decoder networks based on the provided specifications. The first network, dedicated to determining the mean (µ), and the second for the log standard deviation (logσ), both begin with a dense layer mapping from the latent space and go through a sequence of middle layers if specified.

Example

n_latent = 64
µ_neurons = [128, 256]
µ_activation = [relu, relu]
logσ_neurons = [128, 256]
logσ_activation = [relu, relu]
decoder = SplitGaussianLogDecoder(
    n_latent, µ_neurons, µ_activation, logσ_neurons, logσ_activation
)

Notes

• Ensure that the lengths of µneurons with µactivation and logσneurons with logσactivation match respectively.
• If µneurons[end] or logσneurons[end] do not match n_input, the function automatically changes this number to match the right dimensionality

SplitGaussianDecoder(n_input, n_latent, µ_neurons, µ_activation, logσ_neurons, 
            logσ_activation; init=Flux.glorot_uniform)

Constructs and initializes a SplitGaussianDecoder object for variational autoencoders (VAEs). This function sets up two distinct decoder networks, one dedicated for determining the mean (µ) and the other for the standard deviation (σ) of the latent space.

Arguments

• n_input::Int: Dimensionality of the output data (or the data to be reconstructed).
• n_latent::Int: Dimensionality of the latent space.
• µ_neurons::Vector{<:Int}: Vector of layer sizes for the µ decoder network, not including the input latent layer.
• µ_activation::Vector{<:Function}: Activation functions for each µ decoder layer.
• σ_neurons::Vector{<:Int}: Vector of layer sizes for the σ decoder network, not including the input latent layer.
• σ_activation::Vector{<:Function}: Activation functions for each σ decoder layer.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: Initialization function for the network parameters.

Returns

A SplitGaussianDecoder object with two distinct networks initialized with the specified architectures and weights.

Description

This function constructs a SplitGaussianDecoder object, setting up two separate decoder networks based on the provided specifications. The first network, dedicated to determining the mean (µ), and the second for the standard deviation (σ), both begin with a dense layer mapping from the latent space and go through a sequence of middle layers if specified.

Example

n_latent = 64
µ_neurons = [128, 256]
µ_activation = [relu, relu]
σ_neurons = [128, 256]
σ_activation = [relu, relu]
decoder = SplitGaussianDecoder(
    n_latent, µ_neurons, µ_activation, σ_neurons, σ_activation
)

Notes

• Ensure that the lengths of µneurons with µactivation and σneurons with σactivation match respectively.
• If µneurons[end] or σneurons[end] do not match n_input, the function automatically changes this number to match the right dimensionality
• Ensure that σ_neurons[end] maps to a positive value. Activation functions such as softplus are needed to guarantee the positivity of the standard deviation.

    BernoulliDecoder(n_input, n_latent, decoder_neurons, decoder_activation, 
                            output_activation; init=Flux.glorot_uniform)

Constructs and initializes a BernoulliDecoder object designed for variational autoencoders (VAEs). This function sets up a decoder network that maps from a latent space to an output space.

Arguments

• n_input::Int: Dimensionality of the output data (or the data to be reconstructed).
• n_latent::Int: Dimensionality of the latent space.
• decoder_neurons::Vector{<:Int}: Vector of layer sizes for the decoder network, not including the input latent layer and the final output layer.
• decoder_activation::Vector{<:Function}: Activation functions for each decoder layer, not including the final output layer.
• output_activation::Function: Activation function for the final output layer.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: Initialization function for the network parameters.

Returns

A BernoulliDecoder object with the specified architecture and initialized weights.

Description

This function constructs a BernoulliDecoder object, setting up its decoder network based on the provided specifications. The architecture begins with a dense layer mapping from the latent space, goes through a sequence of middle layers if specified, and finally maps to the output space.

The function ensures that there are appropriate activation functions provided for each layer in the decoder_neurons and checks for potential mismatches in length.

Example

n_input = 28*28
n_latent = 64
decoder_neurons = [128, 256]
decoder_activation = [relu, relu]
output_activation = sigmoid
decoder = BernoulliDecoder(
    n_input, 
    n_latent, 
    decoder_neurons, 
    decoder_activation, 
    output_activation
)

Note

Ensure that the lengths of decoderneurons and decoderactivation match, excluding the output layer. Also, the output activation function should return values between 0 and 1, as the decoder models the output data as a Bernoulli distribution.

    CategoricalDecoder(
        size_input, n_latent, decoder_neurons, decoder_activation, 
        output_activation; init=Flux.glorot_uniform
    )

Constructs and initializes a CategoricalDecoder object designed for variational autoencoders (VAEs). This function sets up a decoder network that maps from a latent space to an output space.

Arguments

• size_input::AbstractVector{<:Int}: Dimensionality of the output data (or the data to be reconstructed) in the form of a vector where each element represents the size of a dimension.
• n_latent::Int: Dimensionality of the latent space.
• decoder_neurons::Vector{<:Int}: Vector of layer sizes for the decoder network, not including the input latent layer and the final output layer.
• decoder_activation::Vector{<:Function}: Activation functions for each decoder layer, not including the final output layer.
• output_activation::Function: Activation function for the final output layer.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: Initialization function for the network parameters.

Returns

A CategoricalDecoder object with the specified architecture and initialized weights.

Description

This function constructs a CategoricalDecoder object, setting up its decoder network based on the provided specifications. The architecture begins with a dense layer mapping from the latent space, goes through a sequence of middle layers if specified, and finally maps to the output space.

The function ensures that there are appropriate activation functions provided for each layer in the decoder_neurons and checks for potential mismatches in length.

The output layer uses the identity function as its activation function, and the output is reshaped to match the dimensions specified in size_input. The output_activation function is then applied over the first dimension of the reshaped output.

Note

Ensure that the lengths of decoderneurons and decoderactivation match, excluding the output layer. Also, the output activation function should return values that can be interpreted as probabilities, as the decoder models the output data as a categorical distribution.

CategoricalDecoder(
    n_input, n_latent, decoder_neurons, decoder_activation,
    output_activation; init=Flux.glorot_uniform
)

Constructs and initializes a CategoricalDecoder object designed for variational autoencoders (VAEs). This function sets up a decoder network that maps from a latent space to an output space.

Arguments

• size_input::AbstractVector{<:Int}: Dimensionality of the output data (or the data to be reconstructed).
• n_latent::Int: Dimensionality of the latent space.
• decoder_neurons::Vector{<:Int}: Vector of layer sizes for the decoder network, not including the input latent layer and the final output layer.
• decoder_activation::Vector{<:Function}: Activation functions for each decoder layer, not including the final output layer.
• output_activation::Function: Activation function for the final output layer.

Optional Keyword Arguments

• init::Function=Flux.glorot_uniform: Initialization function for the network parameters.

Returns

A CategoricalDecoder object with the specified architecture and initialized weights.

Description

This function constructs a CategoricalDecoder object, setting up its decoder network based on the provided specifications. The architecture begins with a dense layer mapping from the latent space, goes through a sequence of middle layers if specified, and finally maps to the output space.

The function ensures that there are appropriate activation functions provided for each layer in the decoder_neurons and checks for potential mismatches in length.

Note

Ensure that the lengths of decoderneurons and decoderactivation match, excluding the output layer. Also, the output activation function should return values that can be interpreted as probabilities, as the decoder models the output data as a categorical distribution.

encoder_logposterior(
    z::AbstractVector,
    encoder::AbstractGaussianLogEncoder,
    encoder_output::NamedTuple
)

Computes the log-posterior of the latent variable z given the encoder output under a Gaussian distribution with mean and standard deviation given by the encoder.

Arguments

• z::AbstractVector: The latent variable for which the log-posterior is to be computed.
• encoder::AbstractGaussianLogEncoder: The encoder of the VAE, which is not used in the computation of the log-posterior. This argument is only used to know which method to call.
• encoder_output::NamedTuple: The output of the encoder, which includes the mean and log standard deviation of the Gaussian distribution.

Returns

• logposterior::T: The computed log-posterior of the latent variable z given the encoder output.

Description

The function computes the log-posterior of the latent variable z given the encoder output under a Gaussian distribution. The mean and log standard deviation of the Gaussian distribution are extracted from the encoder_output. The standard deviation is then computed by exponentiating the log standard deviation. The log-posterior is computed using the formula for the log-posterior of a Gaussian distribution.

Note

Ensure the dimensions of z match the expected input dimensionality of the encoder.

encoder_logposterior(
    z::AbstractMatrix,
    encoder::AbstractGaussianLogEncoder,
    encoder_output::NamedTuple
)

Computes the log-posterior of the latent variable z given the encoder output under a Gaussian distribution with mean and standard deviation given by the encoder.

Arguments

• z::AbstractMatrix: The latent variable for which the log-posterior is to be computed. Each column of z represents a different data point.
• encoder::AbstractGaussianLogEncoder: The encoder of the VAE, which is not used in the computation of the log-posterior. This argument is only used to know which method to call.
• encoder_output::NamedTuple: The output of the encoder, which includes the mean and log standard deviation of the Gaussian distribution.

Returns

• logposterior::Vector: The computed log-posterior of the latent variable z given the encoder output. Each element of the vector corresponds to a different data point.

Description

The function computes the log-posterior of the latent variable z given the encoder output under a Gaussian distribution. The mean and log standard deviation of the Gaussian distribution are extracted from the encoder_output. The standard deviation is then computed by exponentiating the log standard deviation. The log-posterior is computed using the formula for the log-posterior of a Gaussian distribution.

Note

Ensure the dimensions of z match the expected input dimensionality of the encoder.

encoder_logposterior(
    z::AbstractVector,
    encoder::AbstractGaussianLogEncoder,
    encoder_output::NamedTuple,
    index::Int
)

Computes the log-posterior of the latent variable z for a single data point specified by index given the encoder output under a Gaussian distribution with mean and standard deviation given by the encoder.

Arguments

• z::AbstractVector: The latent variable for which the log-posterior is to be computed.
• encoder::AbstractGaussianLogEncoder: The encoder of the VAE, which is not used in the computation of the log-posterior. This argument is only used to know which method to call.
• encoder_output::NamedTuple: The output of the encoder, which includes the mean and log standard deviation of the Gaussian distribution for multiple data points.
• index::Int: The index of the data point for which the log-posterior is to be computed.

Returns

• logposterior::Float32: The computed log-posterior of the latent variable z for the specified data point given the encoder output.

Description

The function computes the log-posterior of the latent variable z for a single data point specified by index given the encoder output under a Gaussian distribution. The mean and log standard deviation of the Gaussian distribution are extracted from the encoder_output for the specified data point. The standard deviation is then computed by exponentiating the log standard deviation. The log-posterior is computed using the formula for the log-posterior of a Gaussian distribution.

Note

Ensure the dimensions of z match the expected input dimensionality of the encoder. Also, ensure that index is a valid index for the data points in encoder_output.

encoder_kl(
    encoder::AbstractGaussianLogEncoder,
    encoder_output::NamedTuple
)

Calculate the Kullback-Leibler (KL) divergence between the approximate posterior distribution and the prior distribution in a variational autoencoder with a Gaussian encoder.

The KL divergence for a Gaussian encoder with mean encoder_µ and log standard deviation encoder_logσ is computed against a standard Gaussian prior.

Arguments

• encoder::AbstractGaussianLogEncoder: Encoder network. This argument is not used in the computation of the KL divergence, but is included to allow for multiple encoder types to be used with the same function.
• encoder_output::NamedTuple: NamedTuple containing all the encoder outputs. It should have fields μ and logσ representing the mean and log standard deviation of the encoder's output.

Returns

• kl_div::Union{Number, Vector}: The KL divergence for the entire batch of data points. If encoder_µ is a vector, kl_div is a scalar. If encoder_µ is a matrix, kl_div is a vector where each element corresponds to the KL divergence for a batch of data points.

Note

• It is assumed that the mapping from data space to latent parameters (encoder_µ and encoder_logσ) has been performed prior to calling this function. The encoder argument is provided to indicate the type of decoder network used, but it is not used within the function itself.

spherical_logprior(z::AbstractVector, σ::Real=1.0f0)

Computes the log-prior of the latent variable z under a spherical Gaussian distribution with zero mean and standard deviation σ.

Arguments

• z::AbstractVector: The latent variable for which the log-prior is to be computed.
• σ::T=1.0f0: The standard deviation of the spherical Gaussian distribution. Defaults to 1.0f0.

Returns

• logprior::T: The computed log-prior of the latent variable z.

Description

The function computes the log-prior of the latent variable z under a spherical Gaussian distribution with zero mean and standard deviation σ. The log-prior is computed using the formula for the log-prior of a Gaussian distribution.

Note

Ensure the dimension of z matches the expected dimensionality of the latent space.

spherical_logprior(z::AbstractMatrix, σ::Real=1.0f0)

Computes the log-prior of the latent variable z under a spherical Gaussian distribution with zero mean and standard deviation σ.

Arguments

• z::AbstractMatrix: The latent variable for which the log-prior is to be computed. Each column of z represents a different latent variable.
• σ::Real=1.0f0: The standard deviation of the spherical Gaussian distribution. Defaults to 1.0f0.

Returns

• logprior::T: The computed log-prior(s) of the latent variable z.

Description

The function computes the log-prior of the latent variable z under a spherical Gaussian distribution with zero mean and standard deviation σ. The log-prior is computed using the formula for the log-prior of a Gaussian distribution.

Note

Ensure the dimension of z matches the expected dimensionality of the latent space.