1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17// Implements learning rate adaptations common to most stochastic algorithms.
18
19#ifndef LEARNING_STOCHASTIC_LINEAR_LEARNING_RATE_CONTROLLER_INL_H_
20#define LEARNING_STOCHASTIC_LINEAR_LEARNING_RATE_CONTROLLER_INL_H_
21
22#include <cmath>
23#include "common_defs.h"
24
25namespace learning_stochastic_linear {
26
27class LearningRateController {
28 public:
29  LearningRateController() {
30    iteration_num_ = 1;
31    lambda_ = 1.0;
32    mini_batch_size_ = 1;
33    mini_batch_counter_ = 1;
34    sample_num_ = 1;
35    mode_ = INV_LINEAR;
36    is_first_sample_ = true;
37  }
38  ~LearningRateController() {}
39  // Getters and Setters for learning rate parameter lambda_
40  double GetLambda() const {
41    return lambda_;
42  }
43  void SetLambda(double lambda) {
44    lambda_ = lambda;
45  }
46  // Operations on current iteration number
47  void SetIterationNumber(uint64 num) {
48    iteration_num_ = num;
49  }
50  void IncrementIteration() {
51    ++iteration_num_;
52  }
53  uint64 GetIterationNumber() const {
54    return iteration_num_;
55  }
56  // Mini batch operations
57  uint64 GetMiniBatchSize() const {
58    return mini_batch_size_;
59  }
60  void SetMiniBatchSize(uint64 size) {
61    //CHECK_GT(size, 0);
62    mini_batch_size_ = size;
63  }
64  void IncrementSample() {
65    // If this is the first sample we've already counted it to prevent NaNs
66    // in the learning rate computation
67    if (is_first_sample_) {
68      is_first_sample_ = false;
69      return;
70    }
71    ++sample_num_;
72    if (1 == mini_batch_size_) {
73      IncrementIteration();
74      mini_batch_counter_ = 0;
75    } else {
76      ++mini_batch_counter_;
77      if ((mini_batch_counter_ % mini_batch_size_ == 0)) {
78        IncrementIteration();
79        mini_batch_counter_ = 0;
80      }
81    }
82  }
83  uint64 GetMiniBatchCounter() const {
84    return mini_batch_counter_;
85  }
86  // Getters and setters for adaptation mode
87  AdaptationMode GetAdaptationMode() const {
88    return mode_;
89  }
90  void SetAdaptationMode(AdaptationMode m) {
91    mode_ = m;
92  }
93  double GetLearningRate() const {
94    if (mode_ == CONST) {
95      return (1.0 / (lambda_ * mini_batch_size_));
96    } else if (mode_ == INV_LINEAR) {
97      return (1.0 / (lambda_ * iteration_num_ * mini_batch_size_));
98    } else if (mode_ == INV_QUADRATIC) {
99      return (1.0 / (lambda_ *
100                     mini_batch_size_ *
101                     (static_cast<double>(iteration_num_) * iteration_num_)));
102    } else if (mode_ == INV_SQRT) {
103      return (1.0 / (lambda_ *
104                     mini_batch_size_ *
105                     sqrt((double)iteration_num_)));
106    }
107    return 0;
108  }
109  void CopyFrom(const LearningRateController &other) {
110    iteration_num_ = other.iteration_num_;
111    sample_num_ = other.sample_num_;
112    mini_batch_size_ = other.mini_batch_size_;
113    mini_batch_counter_ = other.mini_batch_counter_;
114    mode_ = other.mode_;
115    is_first_sample_ = other.is_first_sample_;
116  }
117 private:
118  uint64 iteration_num_;
119  uint64 sample_num_;
120  uint64 mini_batch_size_;
121  uint64 mini_batch_counter_;
122  double lambda_;
123  AdaptationMode mode_;
124  bool is_first_sample_;
125};
126}  // namespace learning_stochastic_linear
127#endif  // LEARNING_STOCHASTIC_LINEAR_LEARNING_RATE_CONTROLLER_INL_H_
128