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// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/assist_ranker/example_preprocessing.h"
#include "base/numerics/ranges.h"
#include "base/strings/strcat.h"
#include "base/strings/string_number_conversions.h"
#include "components/assist_ranker/ranker_example_util.h"
#include "third_party/protobuf/src/google/protobuf/map.h"
#include "third_party/protobuf/src/google/protobuf/repeated_field.h"
namespace assist_ranker {
using google::protobuf::Map;
using google::protobuf::MapPair;
using google::protobuf::RepeatedField;
// Initialize.
const char ExamplePreprocessor::kMissingFeatureDefaultName[] =
"_MissingFeature";
const char ExamplePreprocessor::kVectorizedFeatureDefaultName[] =
"_VectorizedFeature";
std::string ExamplePreprocessor::FeatureFullname(
const std::string& feature_name,
const std::string& feature_value) {
return feature_value.empty()
? feature_name
: base::StrCat({feature_name, "_", feature_value});
}
int ExamplePreprocessor::Process(RankerExample* const example,
const bool clear_other_features) const {
return AddMissingFeatures(example) | NormalizeFeatures(example) |
AddBucketizedFeatures(example) | ConvertToStringFeatures(example) |
Vectorization(example, clear_other_features);
}
int ExamplePreprocessor::AddMissingFeatures(
RankerExample* const example) const {
Map<std::string, Feature>& feature_map = *example->mutable_features();
for (const std::string& feature_name : config_.missing_features()) {
// If a feature is missing in the example, set the place.
if (feature_map.find(feature_name) == feature_map.end()) {
feature_map[kMissingFeatureDefaultName]
.mutable_string_list()
->add_string_value(feature_name);
}
}
return kSuccess;
}
int ExamplePreprocessor::AddBucketizedFeatures(
RankerExample* const example) const {
int error_code = kSuccess;
Map<std::string, Feature>& feature_map = *example->mutable_features();
for (const MapPair<std::string, ExamplePreprocessorConfig::Boundaries>&
bucketizer : config_.bucketizers()) {
const std::string& feature_name = bucketizer.first;
// Simply continue if the feature is missing. The missing feature will later
// on be handled as missing one_hot feature, and it's up to the user how to
// handle this missing feature.
Feature feature;
if (!SafeGetFeature(feature_name, *example, &feature)) {
continue;
}
// Get feature value as float. Only int32 or float value is supported for
// Bucketization. Continue if the type_case is not int32 or float.
float value = 0;
switch (feature.feature_type_case()) {
case Feature::kInt32Value:
value = static_cast<float>(feature.int32_value());
break;
case Feature::kFloatValue:
value = feature.float_value();
break;
default:
DVLOG(2) << "Can't bucketize feature type: "
<< feature.feature_type_case();
error_code |= kNonbucketizableFeatureType;
continue;
}
// Get the bucket from the boundaries; the first index that value<boundary.
const RepeatedField<float>& boundaries = bucketizer.second.boundaries();
int index = 0;
for (; index < boundaries.size(); ++index) {
if (value < boundaries[index])
break;
}
// Set one hot feature as features[feature_name] = "index";
feature_map[feature_name].set_string_value(base::IntToString(index));
}
return error_code;
}
int ExamplePreprocessor::NormalizeFeatures(RankerExample* example) const {
int error_code = kSuccess;
for (const MapPair<std::string, float>& pair : config_.normalizers()) {
const std::string& feature_name = pair.first;
float feature_value = 0.0f;
if (GetFeatureValueAsFloat(feature_name, *example, &feature_value)) {
if (pair.second == 0.0f) {
error_code |= kNormalizerIsZero;
} else {
feature_value = feature_value / pair.second;
}
// Truncate to be within [-1.0, 1.0].
feature_value = base::ClampToRange(feature_value, -1.0f, 1.0f);
(*example->mutable_features())[feature_name].set_float_value(
feature_value);
} else {
error_code |= kNonNormalizableFeatureType;
}
}
return error_code;
}
int ExamplePreprocessor::ConvertToStringFeatures(RankerExample* example) const {
int error_code = kSuccess;
for (const std::string& feature_name : config_.convert_to_string_features()) {
const auto find_feature = example->mutable_features()->find(feature_name);
if (find_feature != example->features().end()) {
auto& feature = find_feature->second;
switch (feature.feature_type_case()) {
case Feature::kBoolValue:
feature.set_string_value(
base::IntToString(static_cast<int>(feature.bool_value())));
break;
case Feature::kInt32Value:
feature.set_string_value(base::IntToString(feature.int32_value()));
break;
case Feature::kStringValue:
break;
default:
LOG(WARNING) << "Can't convert to string feature type: "
<< feature.feature_type_case();
error_code |= kNonConvertibleToStringFeatureType;
continue;
}
}
}
return error_code;
}
int ExamplePreprocessor::Vectorization(RankerExample* example,
const bool clear_other_features) const {
if (config_.feature_indices().empty()) {
DVLOG(2) << "Feature indices are empty, can't vectorize.";
return kSuccess;
}
Feature vectorized_features;
vectorized_features.mutable_float_list()->mutable_float_value()->Resize(
config_.feature_indices().size(), 0.0);
int error_code = kSuccess;
for (const auto& field : ExampleFloatIterator(*example)) {
error_code |= field.error;
if (field.error != kSuccess) {
continue;
}
const auto find_index = config_.feature_indices().find(field.fullname);
// If the feature_fullname is inside the indices map, then set the place.
if (find_index != config_.feature_indices().end()) {
vectorized_features.mutable_float_list()->set_float_value(
find_index->second, field.value);
} else {
DVLOG(2) << "Feature has no index: " << field.fullname;
error_code |= kNoFeatureIndexFound;
}
}
if (clear_other_features) {
example->clear_features();
}
(*example->mutable_features())[kVectorizedFeatureDefaultName] =
vectorized_features;
return error_code;
}
ExampleFloatIterator::Field ExampleFloatIterator::operator*() const {
const std::string& feature_name = feature_iterator_->first;
const Feature& feature = feature_iterator_->second;
Field field = {feature_name, 1.0f, ExamplePreprocessor::kSuccess};
switch (feature.feature_type_case()) {
case Feature::kBoolValue:
field.value = static_cast<float>(feature.bool_value());
break;
case Feature::kInt32Value:
field.value = static_cast<float>(feature.int32_value());
break;
case Feature::kFloatValue:
field.value = feature.float_value();
break;
case Feature::kStringValue:
field.fullname = ExamplePreprocessor::FeatureFullname(
feature_name, feature.string_value());
break;
case Feature::kStringList:
if (string_list_index_ < feature.string_list().string_value_size()) {
const std::string& string_value =
feature.string_list().string_value(string_list_index_);
field.fullname =
ExamplePreprocessor::FeatureFullname(feature_name, string_value);
} else {
// This happens when a string list field is added without any value.
field.error = ExamplePreprocessor::kInvalidFeatureListIndex;
}
break;
default:
field.error = ExamplePreprocessor::kInvalidFeatureType;
DVLOG(2) << "Feature type not supported: "
<< feature.feature_type_case();
break;
}
return field;
}
ExampleFloatIterator& ExampleFloatIterator::operator++() {
const Feature& feature = feature_iterator_->second;
switch (feature.feature_type_case()) {
case Feature::kBoolValue:
case Feature::kInt32Value:
case Feature::kFloatValue:
case Feature::kStringValue:
++feature_iterator_;
break;
case Feature::kStringList:
if (string_list_index_ < feature.string_list().string_value_size() - 1) {
// If not at the last element, advance the index.
++string_list_index_;
} else {
// If at the last element, advance the feature_iterator.
string_list_index_ = 0;
++feature_iterator_;
}
break;
default:
++feature_iterator_;
DVLOG(2) << "Feature type not supported: "
<< feature.feature_type_case();
}
return *this;
}
} // namespace assist_ranker
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