ai.djl.nn.recurrent

Class GRU

java.lang.Object

ai.djl.nn.AbstractBlock

ai.djl.nn.ParameterBlock

ai.djl.nn.recurrent.RecurrentCell

ai.djl.nn.recurrent.GRU

All Implemented Interfaces:

Block

public class GRU
extends RecurrentCell

Applies GRU (Gated Recurrent Unit) recurrent layer to input.

Reference paper - Gated Recurrent Unit - Cho et al. 2014. http://arxiv.org/abs/1406.1078. The definition of GRU here is slightly different from the paper but compatible with CUDNN.

$$ \begin{split}\begin{array}{ll} r_t = \mathrm{sigmoid}(W_{ir} x_t + b_{ir} + W_{hr} h_{(t-1)} + b_{hr}) \\ z_t = \mathrm{sigmoid}(W_{iz} x_t + b_{iz} + W_{hz} h_{(t-1)} + b_{hz}) \\ n_t = \tanh(W_{in} x_t + b_{in} + r_t * (W_{hn} h_{(t-1)}+ b_{hn})) \\ h_t = (1 - z_t) * n_t + z_t * h_{(t-1)} \\ \end{array}\end{split} $$

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GRU.Builder The Builder to construct a GRU type of Block.

Nested classes/interfaces inherited from class ai.djl.nn.recurrent.RecurrentCell

RecurrentCell.BaseBuilder<T extends RecurrentCell.BaseBuilder>

Field Summary

Fields inherited from class ai.djl.nn.recurrent.RecurrentCell

dropRate, mode, numStackedLayers, stateOutputs, stateSize, useBidirectional, useSequenceLength

Fields inherited from class ai.djl.nn.AbstractBlock

inputNames, inputShapes

Method Summary

Modifier and Type	Method and Description
void	beforeInitialize(Shape[] inputShapes) Performs any action necessary before initialization.
NDList	forward(ParameterStore parameterStore, NDList inputs, ai.djl.util.PairList<java.lang.String,java.lang.Object> params) Applies the operating function of the block once.
java.util.List<Parameter>	getDirectParameters() Returns a list of all the direct parameters of the block.
Shape[]	getOutputShapes(NDManager manager, Shape[] inputs) Returns the expected output shapes of the block for the specified input shapes.
Shape	getParameterShape(java.lang.String name, Shape[] inputShapes) Returns the shape of the specified direct parameter of this block given the shapes of the input to the block.
void	loadParameters(NDManager manager, java.io.DataInputStream is) Loads the parameters from the given input stream.
void	saveParameters(java.io.DataOutputStream os) Writes the parameters of the block to the given outputStream.

Methods inherited from class ai.djl.nn.recurrent.RecurrentCell

validateInputSize

Methods inherited from class ai.djl.nn.ParameterBlock

getChildren, initialize, toString

Methods inherited from class ai.djl.nn.AbstractBlock

cast, clear, describeInput, getParameters, isInitialized, setInitializer, setInitializer

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface ai.djl.nn.Block

forward, validateLayout

Method Detail

forward

public NDList forward(ParameterStore parameterStore,
                      NDList inputs,
                      ai.djl.util.PairList<java.lang.String,java.lang.Object> params)

Applies the operating function of the block once. This method should be called only on blocks that are initialized.

Parameters:

parameterStore - the parameter store

inputs - the input NDList

params - optional parameters

Returns:

the output of the forward pass

getOutputShapes

public Shape[] getOutputShapes(NDManager manager,
                               Shape[] inputs)

Returns the expected output shapes of the block for the specified input shapes.

Parameters:

manager - an NDManager

inputs - the shapes of the inputs

Returns:

the expected output shapes of the block

getDirectParameters

public java.util.List<Parameter> getDirectParameters()

Returns a list of all the direct parameters of the block.

Returns:

the list of Parameter

beforeInitialize

public void beforeInitialize(Shape[] inputShapes)

Performs any action necessary before initialization.

Overrides:

beforeInitialize in class AbstractBlock

Parameters:

inputShapes - the expected shapes of the input

getParameterShape

public Shape getParameterShape(java.lang.String name,
                               Shape[] inputShapes)

Returns the shape of the specified direct parameter of this block given the shapes of the input to the block.

Parameters:

name - the name of the parameter

inputShapes - the shapes of the input to the block

Returns:

the shape of the parameter specified

saveParameters

public void saveParameters(java.io.DataOutputStream os)
                    throws java.io.IOException

Writes the parameters of the block to the given outputStream.

Parameters:

os - the outputstream to save the parameters to

Throws:

java.io.IOException - if an I/O error occurs

loadParameters

public void loadParameters(NDManager manager,
                           java.io.DataInputStream is)
                    throws java.io.IOException,
                           MalformedModelException

Loads the parameters from the given input stream.

Parameters:

manager - an NDManager to create the parameter arrays

is - the inputstream that stream the parameter values

Throws:

java.io.IOException - if an I/O error occurs

MalformedModelException - if the model file is corrupted or unsupported