com.intel.analytics.bigdl.nn.ParallelCriterion.scala Maven / Gradle / Ivy

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/*
 * Copyright 2016 The BigDL Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License 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 com.intel.analytics.bigdl.nn

import com.intel.analytics.bigdl.nn.abstractnn.{Activity, AbstractCriterion}
import com.intel.analytics.bigdl.tensor.TensorNumericMath.TensorNumeric
import com.intel.analytics.bigdl.utils.{T, Table}

import scala.reflect.ClassTag

/**
 * ParallelCriterion is a weighted sum of other criterions each applied to a different input
 * and target. Set repeatTarget = true to share the target for criterions.
 *
 * Use add(criterion[, weight]) method to add criterion. Where weight is a scalar(default 1).
 *
 * @param repeatTarget Whether to share the target for all criterions.
 */

@SerialVersionUID(- 556839979002442525L)
class ParallelCriterion[@specialized(Float, Double) T: ClassTag](val repeatTarget: Boolean = false)
  (implicit ev: TensorNumeric[T]) extends AbstractCriterion[Table, Table, T] {

  // list of sub criterions
  val criterions = T()
  val weights = T()
  val outputs = T()

  def add(
    criterion: AbstractCriterion[_ <: Activity, _ <: Activity, T],
    weight : Double = 1.0): this.type = {
    criterions.insert(criterion)
    weights.insert(ev.fromType(weight))
    outputs.insert(ev.fromType(0))
    this
  }

  override def updateOutput(input: Table, target: Table): T = {
    var output = ev.fromType[Int](0)
    var i = 1
    while(i <= criterions.length()) {
      val currentCriterion = criterions[AbstractCriterion[Activity, Activity, T]](i)
      val currentTarget: Activity = if (repeatTarget) target else target(i)
      outputs(i) = currentCriterion.forward(input(i), currentTarget)
      output = ev.plus(output, ev.times(weights[T](i), outputs(i)))
      i += 1
    }

    output
  }

  override def updateGradInput(input: Table, target: Table): Table = {
    gradInput = Utils.recursiveResizeAs[T](gradInput, input).toTable
    Utils.recursiveFill[T](gradInput, 0)
    var i = 1
    while (i <= criterions.length()) {
      val currentCriterion = criterions[AbstractCriterion[Activity, Activity, T]](i)
      val currentTarget: Activity = if (repeatTarget) target else target(i)
      Utils.recursiveAdd[T](gradInput(i), ev.toType[Double](weights(i)),
        currentCriterion.updateGradInput(input(i), currentTarget))
      i += 1
    }

    gradInput
  }
}

object ParallelCriterion {
  def apply[@specialized(Float, Double) T: ClassTag](
      repeatTarget: Boolean = false)(implicit ev: TensorNumeric[T]) : ParallelCriterion[T] = {
    new ParallelCriterion[T](repeatTarget)
  }
}