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https://github.com/tesseract-ocr/tesseract.git
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263 lines
8.7 KiB
C++
263 lines
8.7 KiB
C++
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// Copyright 2011 Google Inc. All Rights Reserved.
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// Author: rays@google.com (Ray Smith)
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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///////////////////////////////////////////////////////////////////////
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#include "sampleiterator.h"
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#include "indexmapbidi.h"
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#include "shapetable.h"
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#include "trainingsample.h"
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#include "trainingsampleset.h"
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namespace tesseract {
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// ================== SampleIterator Implementation =================
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SampleIterator::SampleIterator()
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: charset_map_(NULL),
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shape_table_(NULL),
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sample_set_(NULL),
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randomize_(false),
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owned_shape_table_(NULL) {
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num_shapes_ = 0;
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Begin();
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}
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SampleIterator::~SampleIterator() {
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Clear();
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}
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void SampleIterator::Clear() {
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delete owned_shape_table_;
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owned_shape_table_ = NULL;
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}
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// See class comment for arguments.
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void SampleIterator::Init(const IndexMapBiDi* charset_map,
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const ShapeTable* shape_table,
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bool randomize,
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TrainingSampleSet* sample_set) {
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Clear();
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charset_map_ = charset_map;
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shape_table_ = shape_table;
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sample_set_ = sample_set;
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randomize_ = randomize;
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if (shape_table_ == NULL && charset_map_ != NULL) {
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// The caller wishes to iterate by class. The easiest way to do this
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// is to create a dummy shape_table_ that we will own.
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int num_fonts = sample_set_->NumFonts();
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owned_shape_table_ = new ShapeTable(sample_set_->unicharset());
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int charsetsize = sample_set_->unicharset().size();
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for (int c = 0; c < charsetsize; ++c) {
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// We always add a shape for each character to keep the index in sync
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// with the unichar_id.
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int shape_id = owned_shape_table_->AddShape(c, 0);
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for (int f = 1; f < num_fonts; ++f) {
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if (sample_set_->NumClassSamples(f, c, true) > 0) {
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owned_shape_table_->AddToShape(shape_id, c, f);
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}
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}
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}
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shape_table_ = owned_shape_table_;
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}
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if (shape_table_ != NULL) {
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num_shapes_ = shape_table_->NumShapes();
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} else {
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num_shapes_ = randomize ? sample_set_->num_samples()
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: sample_set_->num_raw_samples();
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}
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Begin();
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}
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// Iterator functions designed for use with a simple for loop:
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// for (it.Begin(); !it.AtEnd(); it.Next()) {
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// const TrainingSample& sample = it.GetSample();
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// }
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void SampleIterator::Begin() {
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shape_index_ = -1;
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shape_char_index_ = 0;
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num_shape_chars_ = 0;
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shape_font_index_ = 0;
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num_shape_fonts_ = 0;
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sample_index_ = 0;
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num_samples_ = 0;
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// Find the first indexable sample.
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Next();
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}
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bool SampleIterator::AtEnd() const {
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return shape_index_ >= num_shapes_;
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}
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const TrainingSample& SampleIterator::GetSample() const {
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if (shape_table_ != NULL) {
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const UnicharAndFonts* shape_entry = GetShapeEntry();
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int char_id = shape_entry->unichar_id;
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int font_id = shape_entry->font_ids[shape_font_index_];
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return *sample_set_->GetSample(font_id, char_id, sample_index_);
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} else {
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return *sample_set_->GetSample(shape_index_);
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}
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}
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TrainingSample* SampleIterator::MutableSample() const {
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if (shape_table_ != NULL) {
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const UnicharAndFonts* shape_entry = GetShapeEntry();
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int char_id = shape_entry->unichar_id;
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int font_id = shape_entry->font_ids[shape_font_index_];
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return sample_set_->MutableSample(font_id, char_id, sample_index_);
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} else {
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return sample_set_->mutable_sample(shape_index_);
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}
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}
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// Returns the total index (from the original set of samples) of the current
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// sample.
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int SampleIterator::GlobalSampleIndex() const {
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if (shape_table_ != NULL) {
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const UnicharAndFonts* shape_entry = GetShapeEntry();
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int char_id = shape_entry->unichar_id;
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int font_id = shape_entry->font_ids[shape_font_index_];
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return sample_set_->GlobalSampleIndex(font_id, char_id, sample_index_);
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} else {
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return shape_index_;
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}
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}
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// Returns the index of the current sample in compact charset space, so
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// in a 2-class problem between x and y, the returned indices will all be
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// 0 or 1, and have nothing to do with the unichar_ids.
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// If the charset_map_ is NULL, then this is equal to GetSparseClassID().
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int SampleIterator::GetCompactClassID() const {
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return charset_map_ != NULL ? charset_map_->SparseToCompact(shape_index_)
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: GetSparseClassID();
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}
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// Returns the index of the current sample in sparse charset space, so
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// in a 2-class problem between x and y, the returned indices will all be
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// x or y, where x and y may be unichar_ids (no shape_table_) or shape_ids
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// with a shape_table_.
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int SampleIterator::GetSparseClassID() const {
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return shape_table_ != NULL ? shape_index_ : GetSample().class_id();
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}
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// Moves on to the next indexable sample. If the end is reached, leaves
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// the state such that AtEnd() is true.
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void SampleIterator::Next() {
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if (shape_table_ != NULL) {
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// Next sample in this class/font combination.
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++sample_index_;
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if (sample_index_ < num_samples_)
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return;
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// Next font in this class in this shape.
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sample_index_ = 0;
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do {
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++shape_font_index_;
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if (shape_font_index_ >= num_shape_fonts_) {
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// Next unichar in this shape.
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shape_font_index_ = 0;
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++shape_char_index_;
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if (shape_char_index_ >= num_shape_chars_) {
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// Find the next shape that is mapped in the charset_map_.
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shape_char_index_ = 0;
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do {
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++shape_index_;
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} while (shape_index_ < num_shapes_ &&
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charset_map_ != NULL &&
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charset_map_->SparseToCompact(shape_index_) < 0);
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if (shape_index_ >= num_shapes_)
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return; // The end.
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num_shape_chars_ = shape_table_->GetShape(shape_index_).size();
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}
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}
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const UnicharAndFonts* shape_entry = GetShapeEntry();
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num_shape_fonts_ = shape_entry->font_ids.size();
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int char_id = shape_entry->unichar_id;
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int font_id = shape_entry->font_ids[shape_font_index_];
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num_samples_ = sample_set_->NumClassSamples(font_id, char_id, randomize_);
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} while (num_samples_ == 0);
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} else {
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// We are just iterating over the samples.
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++shape_index_;
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}
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}
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// Returns the size of the compact charset space.
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int SampleIterator::CompactCharsetSize() const {
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return charset_map_ != NULL ? charset_map_->CompactSize()
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: SparseCharsetSize();
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}
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// Returns the size of the sparse charset space.
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int SampleIterator::SparseCharsetSize() const {
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return charset_map_ != NULL
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? charset_map_->SparseSize()
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: (shape_table_ != NULL ? shape_table_->NumShapes()
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: sample_set_->charsetsize());
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}
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// Apply the supplied feature_space/feature_map transform to all samples
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// accessed by this iterator.
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void SampleIterator::MapSampleFeatures(const IntFeatureMap& feature_map) {
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for (Begin(); !AtEnd(); Next()) {
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TrainingSample* sample = MutableSample();
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sample->MapFeatures(feature_map);
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}
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}
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// Adjust the weights of all the samples to be uniform in the given charset.
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// Returns the number of samples in the iterator.
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int SampleIterator::UniformSamples() {
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int num_good_samples = 0;
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for (Begin(); !AtEnd(); Next()) {
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TrainingSample* sample = MutableSample();
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sample->set_weight(1.0);
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++num_good_samples;
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}
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NormalizeSamples();
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return num_good_samples;
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}
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// Normalize the weights of all the samples in the charset_map so they sum
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// to 1. Returns the minimum assigned sample weight.
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double SampleIterator::NormalizeSamples() {
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double total_weight = 0.0;
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int sample_count = 0;
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for (Begin(); !AtEnd(); Next()) {
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const TrainingSample& sample = GetSample();
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total_weight += sample.weight();
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++sample_count;
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}
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// Normalize samples.
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double min_assigned_sample_weight = 1.0;
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if (total_weight > 0.0) {
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for (Begin(); !AtEnd(); Next()) {
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TrainingSample* sample = MutableSample();
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double weight = sample->weight() / total_weight;
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if (weight < min_assigned_sample_weight)
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min_assigned_sample_weight = weight;
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sample->set_weight(weight);
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}
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}
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return min_assigned_sample_weight;
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}
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// Helper returns the current UnicharAndFont shape_entry.
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const UnicharAndFonts* SampleIterator::GetShapeEntry() const {
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const Shape& shape = shape_table_->GetShape(shape_index_);
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return &shape[shape_char_index_];
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}
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} // namespace tesseract.
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