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sampleiterator.cpp
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1 // Copyright 2011 Google Inc. All Rights Reserved.
2 // Author: rays@google.com (Ray Smith)
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 // http://www.apache.org/licenses/LICENSE-2.0
8 // Unless required by applicable law or agreed to in writing, software
9 // distributed under the License is distributed on an "AS IS" BASIS,
10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11 // See the License for the specific language governing permissions and
12 // limitations under the License.
13 //
15
16 #include "sampleiterator.h"
17
18 #include "indexmapbidi.h"
19 #include "shapetable.h"
20 #include "trainingsample.h"
21 #include "trainingsampleset.h"
22
23 namespace tesseract {
24
25 // ================== SampleIterator Implementation =================
26
27 SampleIterator::SampleIterator()
28 : charset_map_(NULL),
29 shape_table_(NULL),
30 sample_set_(NULL),
31 randomize_(false),
32 owned_shape_table_(NULL) {
33 num_shapes_ = 0;
34 Begin();
35 }
36
37 SampleIterator::~SampleIterator() {
38 Clear();
39 }
40
41 void SampleIterator::Clear() {
42 delete owned_shape_table_;
43 owned_shape_table_ = NULL;
44 }
45
46 // See class comment for arguments.
47 void SampleIterator::Init(const IndexMapBiDi* charset_map,
48 const ShapeTable* shape_table,
49 bool randomize,
50 TrainingSampleSet* sample_set) {
51 Clear();
52 charset_map_ = charset_map;
53 shape_table_ = shape_table;
54 sample_set_ = sample_set;
55 randomize_ = randomize;
56 if (shape_table_ == NULL && charset_map_ != NULL) {
57 // The caller wishes to iterate by class. The easiest way to do this
58 // is to create a dummy shape_table_ that we will own.
59 int num_fonts = sample_set_->NumFonts();
60 owned_shape_table_ = new ShapeTable(sample_set_->unicharset());
61 int charsetsize = sample_set_->unicharset().size();
62 for (int c = 0; c < charsetsize; ++c) {
63 // We always add a shape for each character to keep the index in sync
64 // with the unichar_id.
65 int shape_id = owned_shape_table_->AddShape(c, 0);
66 for (int f = 1; f < num_fonts; ++f) {
67 if (sample_set_->NumClassSamples(f, c, true) > 0) {
68 owned_shape_table_->AddToShape(shape_id, c, f);
69 }
70 }
71 }
72 shape_table_ = owned_shape_table_;
73 }
74 if (shape_table_ != NULL) {
75 num_shapes_ = shape_table_->NumShapes();
76 } else {
77 num_shapes_ = randomize ? sample_set_->num_samples()
78 : sample_set_->num_raw_samples();
79 }
80 Begin();
81 }
82
83 // Iterator functions designed for use with a simple for loop:
84 // for (it.Begin(); !it.AtEnd(); it.Next()) {
85 // const TrainingSample& sample = it.GetSample();
86 // }
87 void SampleIterator::Begin() {
88 shape_index_ = -1;
89 shape_char_index_ = 0;
90 num_shape_chars_ = 0;
91 shape_font_index_ = 0;
92 num_shape_fonts_ = 0;
93 sample_index_ = 0;
94 num_samples_ = 0;
95 // Find the first indexable sample.
96 Next();
97 }
98
99 bool SampleIterator::AtEnd() const {
100 return shape_index_ >= num_shapes_;
101 }
102
103 const TrainingSample& SampleIterator::GetSample() const {
104 if (shape_table_ != NULL) {
105 const UnicharAndFonts* shape_entry = GetShapeEntry();
106 int char_id = shape_entry->unichar_id;
107 int font_id = shape_entry->font_ids[shape_font_index_];
108 return *sample_set_->GetSample(font_id, char_id, sample_index_);
109 } else {
110 return *sample_set_->GetSample(shape_index_);
111 }
112 }
113
114 TrainingSample* SampleIterator::MutableSample() const {
115 if (shape_table_ != NULL) {
116 const UnicharAndFonts* shape_entry = GetShapeEntry();
117 int char_id = shape_entry->unichar_id;
118 int font_id = shape_entry->font_ids[shape_font_index_];
119 return sample_set_->MutableSample(font_id, char_id, sample_index_);
120 } else {
121 return sample_set_->mutable_sample(shape_index_);
122 }
123 }
124
125 // Returns the total index (from the original set of samples) of the current
126 // sample.
127 int SampleIterator::GlobalSampleIndex() const {
128 if (shape_table_ != NULL) {
129 const UnicharAndFonts* shape_entry = GetShapeEntry();
130 int char_id = shape_entry->unichar_id;
131 int font_id = shape_entry->font_ids[shape_font_index_];
132 return sample_set_->GlobalSampleIndex(font_id, char_id, sample_index_);
133 } else {
134 return shape_index_;
135 }
136 }
137
138 // Returns the index of the current sample in compact charset space, so
139 // in a 2-class problem between x and y, the returned indices will all be
140 // 0 or 1, and have nothing to do with the unichar_ids.
141 // If the charset_map_ is NULL, then this is equal to GetSparseClassID().
142 int SampleIterator::GetCompactClassID() const {
143 return charset_map_ != NULL ? charset_map_->SparseToCompact(shape_index_)
144 : GetSparseClassID();
145 }
146 // Returns the index of the current sample in sparse charset space, so
147 // in a 2-class problem between x and y, the returned indices will all be
148 // x or y, where x and y may be unichar_ids (no shape_table_) or shape_ids
149 // with a shape_table_.
150 int SampleIterator::GetSparseClassID() const {
151 return shape_table_ != NULL ? shape_index_ : GetSample().class_id();
152 }
153
154 // Moves on to the next indexable sample. If the end is reached, leaves
155 // the state such that AtEnd() is true.
156 void SampleIterator::Next() {
157 if (shape_table_ != NULL) {
158 // Next sample in this class/font combination.
159 ++sample_index_;
160 if (sample_index_ < num_samples_)
161 return;
162 // Next font in this class in this shape.
163 sample_index_ = 0;
164 do {
165 ++shape_font_index_;
166 if (shape_font_index_ >= num_shape_fonts_) {
167 // Next unichar in this shape.
168 shape_font_index_ = 0;
169 ++shape_char_index_;
170 if (shape_char_index_ >= num_shape_chars_) {
171 // Find the next shape that is mapped in the charset_map_.
172 shape_char_index_ = 0;
173 do {
174 ++shape_index_;
175 } while (shape_index_ < num_shapes_ &&
176 charset_map_ != NULL &&
177 charset_map_->SparseToCompact(shape_index_) < 0);
178 if (shape_index_ >= num_shapes_)
179 return; // The end.
180 num_shape_chars_ = shape_table_->GetShape(shape_index_).size();
181 }
182 }
183 const UnicharAndFonts* shape_entry = GetShapeEntry();
184 num_shape_fonts_ = shape_entry->font_ids.size();
185 int char_id = shape_entry->unichar_id;
186 int font_id = shape_entry->font_ids[shape_font_index_];
187 num_samples_ = sample_set_->NumClassSamples(font_id, char_id, randomize_);
188 } while (num_samples_ == 0);
189 } else {
190 // We are just iterating over the samples.
191 ++shape_index_;
192 }
193 }
194
195 // Returns the size of the compact charset space.
196 int SampleIterator::CompactCharsetSize() const {
197 return charset_map_ != NULL ? charset_map_->CompactSize()
198 : SparseCharsetSize();
199 }
200
201 // Returns the size of the sparse charset space.
202 int SampleIterator::SparseCharsetSize() const {
203 return charset_map_ != NULL
204 ? charset_map_->SparseSize()
205 : (shape_table_ != NULL ? shape_table_->NumShapes()
206 : sample_set_->charsetsize());
207 }
208
209 // Apply the supplied feature_space/feature_map transform to all samples
210 // accessed by this iterator.
211 void SampleIterator::MapSampleFeatures(const IntFeatureMap& feature_map) {
212 for (Begin(); !AtEnd(); Next()) {
213 TrainingSample* sample = MutableSample();
214 sample->MapFeatures(feature_map);
215 }
216 }
217
218 // Adjust the weights of all the samples to be uniform in the given charset.
219 // Returns the number of samples in the iterator.
220 int SampleIterator::UniformSamples() {
221 int num_good_samples = 0;
222 for (Begin(); !AtEnd(); Next()) {
223 TrainingSample* sample = MutableSample();
224 sample->set_weight(1.0);
225 ++num_good_samples;
226 }
227 NormalizeSamples();
228 return num_good_samples;
229 }
230
231 // Normalize the weights of all the samples in the charset_map so they sum
232 // to 1. Returns the minimum assigned sample weight.
233 double SampleIterator::NormalizeSamples() {
234 double total_weight = 0.0;
235 int sample_count = 0;
236 for (Begin(); !AtEnd(); Next()) {
237 const TrainingSample& sample = GetSample();
238 total_weight += sample.weight();
239 ++sample_count;
240 }
241 // Normalize samples.
242 double min_assigned_sample_weight = 1.0;
243 if (total_weight > 0.0) {
244 for (Begin(); !AtEnd(); Next()) {
245 TrainingSample* sample = MutableSample();
246 double weight = sample->weight() / total_weight;
247 if (weight < min_assigned_sample_weight)
248 min_assigned_sample_weight = weight;
249 sample->set_weight(weight);
250 }
251 }
252 return min_assigned_sample_weight;
253 }
254
255 // Helper returns the current UnicharAndFont shape_entry.
256 const UnicharAndFonts* SampleIterator::GetShapeEntry() const {
257 const Shape& shape = shape_table_->GetShape(shape_index_);
258 return &shape[shape_char_index_];
259 }
260
261 } // namespace tesseract.
262