com.intel.analytics.bigdl.nn.MultiLabelSoftMarginCriterion.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.TensorCriterion
import com.intel.analytics.bigdl.tensor.Tensor
import com.intel.analytics.bigdl.tensor.TensorNumericMath.TensorNumeric

import scala.reflect.ClassTag

/**
 *
 * A MultiLabel multiclass criterion based on sigmoid:

 * the loss is:
 * l(x,y) = - sum_i y[i] * log(p[i]) + (1 - y[i]) * log (1 - p[i])
 * where p[i] = exp(x[i]) / (1 + exp(x[i]))

 * and with weights:
 * l(x,y) = - sum_i weights[i] (y[i] * log(p[i]) + (1 - y[i]) * log (1 - p[i]))
 */

@SerialVersionUID(6780540545644361024L)
class MultiLabelSoftMarginCriterion[T: ClassTag]
(var weights: Tensor[T] = null, sizeAverage: Boolean = true)
  (implicit ev: TensorNumeric[T]) extends TensorCriterion[T] {
  var lsm = new Sigmoid[T]()
  var nll = new BCECriterion[T](weights)

  override def updateOutput(input: Tensor[T], target: Tensor[T]): T = {
    var _input: Tensor[T] = input
    var _target: Tensor[T] = target

    if (input.nElement() != 1) {
      _input = input.clone().squeeze()
    }

    if (target.nElement() != 1) {
      _target = target.clone().squeeze()
    }

    lsm.updateOutput(_input)
    nll.updateOutput(lsm.output, _target)
    output = nll.output

    output
  }

  override def updateGradInput(input: Tensor[T], target: Tensor[T]): Tensor[T] = {
    val size = input.size()
    var _input: Tensor[T] = null
    var _target: Tensor[T] = null

    if (input.nElement() != 1) {
      _input = input.clone().squeeze()
    }

    if (target.nElement() != 1) {
      _target = target.squeeze()
    }

    nll.updateGradInput(lsm.output, _target)
    lsm.updateGradInput(_input, nll.gradInput)
    gradInput = lsm.gradInput.view(size)

    gradInput
  }

  override def canEqual(other: Any): Boolean = other.isInstanceOf[MultiLabelSoftMarginCriterion[T]]

  override def equals(other: Any): Boolean = other match {
    case that: MultiLabelSoftMarginCriterion[T] =>
      (that canEqual this) &&
        gradInput == that.gradInput &&
        lsm == that.lsm &&
        nll == that.nll &&
        weights == that.weights
    case _ => false
  }

  override def hashCode(): Int = {
    def getHashCode(x: Any) = if (x == null) 0 else x.hashCode()
    val state = Seq(gradInput, lsm, nll, weights)
    state.map(getHashCode).foldLeft(0)((a, b) => 31 * a + b)
  }


  override def toString: String = s"MultiLabelSoftMarginCriterion($weights)"
}

object MultiLabelSoftMarginCriterion {
  def apply[@specialized(Float, Double) T: ClassTag](
      weights: Tensor[T] = null,
      sizeAverage: Boolean = true
  )(implicit ev: TensorNumeric[T]): MultiLabelSoftMarginCriterion[T] = {
    new MultiLabelSoftMarginCriterion[T](weights, sizeAverage)
  }
}