ai.djl.nn.SequentialBlock Maven / Gradle / Ivy
/*
* Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
* with the License. A copy of the License is located at
*
* http://aws.amazon.com/apache2.0/
*
* or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
* OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
* and limitations under the License.
*/
package ai.djl.nn;
import ai.djl.MalformedModelException;
import ai.djl.ndarray.NDList;
import ai.djl.ndarray.NDManager;
import ai.djl.ndarray.types.DataType;
import ai.djl.ndarray.types.Shape;
import ai.djl.training.ParameterStore;
import ai.djl.util.PairList;
import java.io.DataInputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collection;
import java.util.function.Function;
/**
* {@code SequentialBlock} is a {@link Block} whose children form a chain of blocks with each child
* block feeding its output to the next. The output of the last child is returned as the output of
* the {@code SequentialBlock}.
*
* {@code SequentialBlock} has no direct parameters.
*/
public class SequentialBlock extends AbstractBlock {
private static final byte VERSION = 2;
/**
* Creates an empty sequential block. Use {@code add} and {@code addAll} to add blocks to be
* executed in sequence.
*/
public SequentialBlock() {
super(VERSION);
}
/**
* Adds an array of blocks to be executed in sequence, in order.
*
* @param blocks the array of blocks
* @return this block
*/
public SequentialBlock addAll(Block... blocks) {
this.addAll(Arrays.asList(blocks));
return this;
}
/**
* Adds a {@link Collection} of blocks to be executed in sequence, in order.
*
* @param blocks the {@link Collection} of blocks
* @return this block
*/
public SequentialBlock addAll(Collection blocks) {
blocks.forEach(this::add);
return this;
}
/**
* Adds the given {@link Block} to the block to be executed in order.
*
* @param block the block to be added to the sequence of blocks
* @return this block
*/
public SequentialBlock add(Block block) {
if (block != null) {
addChildBlock(block.getClass().getSimpleName(), block);
}
return this;
}
/**
* Adds a {@link LambdaBlock} that applies the given function to the sequence of blocks.
*
* @param f the function forms the {@link LambdaBlock}
* @return this block
*/
public SequentialBlock add(Function f) {
add(new LambdaBlock(f));
return this;
}
/** Removes the {@link Block} added last from the sequence of blocks. */
public void removeLastBlock() {
children.remove(children.size() - 1);
}
/**
* Replaces the {@link Block} last added from the sequence of blocks, and adds the given block.
*
* @param block the block to replace the last block with
*/
public void replaceLastBlock(Block block) {
removeLastBlock();
if (block != null) {
add(block);
}
}
/** {@inheritDoc} */
@Override
public NDList forward(
ParameterStore parameterStore,
NDList inputs,
boolean training,
PairList params) {
NDList current = inputs;
for (Block block : children.values()) {
current = block.forward(parameterStore, current, training);
}
return current;
}
/** {@inheritDoc} */
@Override
public void initializeChildBlocks(NDManager manager, DataType dataType, Shape... inputShapes) {
Shape[] shapes = inputShapes;
for (Block child : getChildren().values()) {
shapes = child.initialize(manager, dataType, shapes);
}
}
/** {@inheritDoc} */
@Override
public Shape[] getOutputShapes(NDManager manager, Shape[] inputs) {
if (children.isEmpty()) {
throw new IllegalArgumentException("The sequential block is empty");
}
Shape[] current = inputs;
for (Block block : children.values()) {
current = block.getOutputShapes(manager, current);
}
return current;
}
/** {@inheritDoc} */
@Override
public void loadMetadata(byte version, DataInputStream is)
throws IOException, MalformedModelException {
if (version == VERSION) {
readInputShapes(is);
} else if (version != 1) {
throw new MalformedModelException("Unsupported encoding version: " + version);
}
}
/** {@inheritDoc} */
@Override
public String toString() {
StringBuilder sb = new StringBuilder(200);
sb.append("Sequential(\n");
for (Block block : children.values()) {
String blockString = block.toString().replaceAll("(?m)^", "\t");
sb.append(blockString).append('\n');
}
sb.append(')');
return sb.toString();
}
}