com.intel.analytics.bigdl.dllib.optim.Adagrad.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.dllib.optim

import com.intel.analytics.bigdl.dllib.tensor.TensorNumericMath.TensorNumeric
import com.intel.analytics.bigdl.dllib.tensor.Tensor
import com.intel.analytics.bigdl.dllib.utils.{T, Table}

import scala.reflect.ClassTag

/**
 * An implementation of Adagrad. See the original paper:
 * http://jmlr.org/papers/volume12/duchi11a/duchi11a.pdf
 * @param learningRate learning rate
 * @param learningRateDecay learning rate decay
 * @param weightDecay weight decay
 * @tparam T
 */
class Adagrad[@specialized(Float, Double) T: ClassTag](
    var learningRate: Double = 1e-3,
    var learningRateDecay: Double = 0.0,
    var weightDecay: Double = 0.0
  )(implicit ev: TensorNumeric[T]) extends OptimMethod[T] {

  /**
   * Adagrad implementation for Adagrad
   *
   * @param feval     a function that takes a single input (X), the point of a evaluation, and
   *                  returns f(X) and df/dX
   * @param parameter the initial point
   * @return the new x vector and the function list, evaluated before the update
   */
  override def optimize(feval: (Tensor[T]) => (T, Tensor[T]), parameter: Tensor[T]
                       ): (Tensor[T], Array[T]) = {

    val lr = this.learningRate
    val lrd = this.learningRateDecay
    val nevals = state.get[Int]("evalCounter").getOrElse(0)
    val wd = this.weightDecay

    val (fx, dfdx) = feval(parameter)

    if (wd != 0) {
      dfdx.add(ev.fromType[Double](wd), parameter)
    }

    val clr = lr / (1 + nevals * lrd)

    val (_paramVariance, _paramStd) =
      if (state.get[Tensor[T]]("paramVariance").isDefined) {
        (state.get[Tensor[T]]("paramVariance").get, state.get[Tensor[T]]("paramStd").get)
      } else {
        (Tensor[T]().resizeAs(dfdx).zero(), Tensor[T]().resizeAs(dfdx))
      }

    _paramVariance.addcmul(ev.fromType[Int](1), dfdx, dfdx)
    _paramStd.resizeAs(_paramVariance).copy(_paramVariance).sqrt()
    parameter.addcdiv(ev.fromType[Double](-clr), dfdx, _paramStd.add(ev.fromType[Double](1e-10)))

    state("evalCounter") = nevals + 1
    state("paramVariance") = _paramVariance // vector of temporal variances of parameters
    state("paramStd") = _paramStd

    (parameter, Array(fx))
  }

  override def loadFromTable(config: Table): this.type = {
    this.learningRate = config.get[Double]("learningRate").getOrElse(this.learningRate)
    this.learningRateDecay = config.get[Double]("learningRateDecay")
      .getOrElse(this.learningRateDecay)
    this.weightDecay = config.get[Double]("weightDecay").getOrElse(this.weightDecay)
    this
  }

  override def clearHistory(): Unit = {
    state.delete("paramVariance")
    state.delete("paramStd")
  }

  override def getLearningRate(): Double = this.learningRate
}