Add bucketization support for GLR model.

(1) Add generic logstic regression to support preprocessed model.

(2) Also add validation logic in binary classifer to prevent misuse
preprocessed_model with non-preprocessed_model.

Change-Id: Idf3f531c8d7bd45d31a45f6e54be0752a02334d1
Reviewed-on: https://chromium-review.googlesource.com/885541
Commit-Queue: Charles . <charleszhao@chromium.org>
Reviewed-by: Philippe Hamel <hamelphi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532316}

components/assist_ranker/binary_classifier_predictor.cc

@@ -75,6 +75,25 @@ RankerModelStatus BinaryClassifierPredictor::ValidateModel(
     DVLOG(0) << "Model is incompatible.";
     return RankerModelStatus::INCOMPATIBLE;
   }
+  const GenericLogisticRegressionModel& glr =
+      model.proto().logistic_regression();
+  if (glr.is_preprocessed_model()) {
+    if (glr.fullname_weights().empty() || !glr.weights().empty()) {
+      DVLOG(0) << "Model is incompatible. Preprocessed model should use "
+                  "fullname_weights.";
+      return RankerModelStatus::INCOMPATIBLE;
+    }
+    if (!glr.preprocessor_config().feature_indices().empty()) {
+      DVLOG(0) << "Preprocessed model doesn't need feature indices.";
+      return RankerModelStatus::INCOMPATIBLE;
+    }
+  } else {
+    if (!glr.fullname_weights().empty() || glr.weights().empty()) {
+      DVLOG(0) << "Model is incompatible. Non-preprocessed model should use "
+                  "weights.";
+      return RankerModelStatus::INCOMPATIBLE;
+    }
+  }
   return RankerModelStatus::OK;
 }
 

components/assist_ranker/binary_classifier_predictor_unittest.cc

@@ -31,6 +31,7 @@ class BinaryClassifierPredictorTest : public ::testing::Test {
 
  protected:
   const std::string feature_ = "feature";
+  const float weight_ = 1.0;
   const float threshold_ = 0.5;
 };
 
@@ -68,7 +69,7 @@ BinaryClassifierPredictorTest::GetSimpleLogisticRegressionModel() {
   GenericLogisticRegressionModel lr_model;
   lr_model.set_bias(-0.5);
   lr_model.set_threshold(threshold_);
-  (*lr_model.mutable_weights())[feature_].set_scalar(1.0);
+  (*lr_model.mutable_weights())[feature_].set_scalar(weight_);
   return lr_model;
 }
 
@@ -132,4 +133,33 @@ TEST_F(BinaryClassifierPredictorTest, GenericLogisticRegressionModel) {
   EXPECT_LT(float_response, threshold_);
 }
 
+TEST_F(BinaryClassifierPredictorTest,
+       GenericLogisticRegressionPreprocessedModel) {
+  auto ranker_model = std::make_unique<RankerModel>();
+  auto& glr = *ranker_model->mutable_proto()->mutable_logistic_regression();
+  glr = GetSimpleLogisticRegressionModel();
+  glr.clear_weights();
+  glr.set_is_preprocessed_model(true);
+  (*glr.mutable_fullname_weights())[feature_] = weight_;
+
+  auto predictor = InitPredictor(std::move(ranker_model), GetConfig());
+  EXPECT_TRUE(predictor->IsReady());
+
+  RankerExample ranker_example;
+  auto& features = *ranker_example.mutable_features();
+  features[feature_].set_bool_value(true);
+  bool bool_response;
+  EXPECT_TRUE(predictor->Predict(ranker_example, &bool_response));
+  EXPECT_TRUE(bool_response);
+  float float_response;
+  EXPECT_TRUE(predictor->PredictScore(ranker_example, &float_response));
+  EXPECT_GT(float_response, threshold_);
+
+  features[feature_].set_bool_value(false);
+  EXPECT_TRUE(predictor->Predict(ranker_example, &bool_response));
+  EXPECT_FALSE(bool_response);
+  EXPECT_TRUE(predictor->PredictScore(ranker_example, &float_response));
+  EXPECT_LT(float_response, threshold_);
+}
+
 }  // namespace assist_ranker

components/assist_ranker/generic_logistic_regression_inference.cc

@@ -7,6 +7,7 @@
 #include <cmath>
 
 #include "base/logging.h"
+#include "components/assist_ranker/example_preprocessing.h"
 #include "components/assist_ranker/ranker_example_util.h"
 
 namespace assist_ranker {
@@ -24,6 +25,7 @@ GenericLogisticRegressionInference::GenericLogisticRegressionInference(
 float GenericLogisticRegressionInference::PredictScore(
     const RankerExample& example) {
   float activation = 0.0f;
+  if (!proto_.is_preprocessed_model()) {
     for (const auto& weight_it : proto_.weights()) {
       const std::string& feature_name = weight_it.first;
       const FeatureWeight& feature_weight = weight_it.second;
@@ -72,6 +74,20 @@ float GenericLogisticRegressionInference::PredictScore(
         }
       }
     }
+  } else {
+    RankerExample processed_example = example;
+    ExamplePreprocessor(proto_.preprocessor_config())
+        .Process(&processed_example);
+    for (const auto& field : ExampleFloatIterator(processed_example)) {
+      if (field.error != ExamplePreprocessor::kSuccess)
+        continue;
+      const auto& find_weight = proto_.fullname_weights().find(field.fullname);
+      if (find_weight != proto_.fullname_weights().end()) {
+        activation += find_weight->second * field.value;
+      }
+    }
+  }
+
   return Sigmoid(proto_.bias() + activation);
 }
 

components/assist_ranker/generic_logistic_regression_inference_unittest.cc

@@ -3,10 +3,13 @@
 // found in the LICENSE file.
 
 #include "components/assist_ranker/generic_logistic_regression_inference.h"
+#include "components/assist_ranker/example_preprocessing.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/protobuf/src/google/protobuf/map.h"
 
 namespace assist_ranker {
+using ::google::protobuf::Map;
 
 class GenericLogisticRegressionInferenceTest : public testing::Test {
  protected:
@@ -19,11 +22,33 @@ class GenericLogisticRegressionInferenceTest : public testing::Test {
     weights[scalar1_name_].set_scalar(scalar1_weight_);
     weights[scalar2_name_].set_scalar(scalar2_weight_);
     weights[scalar3_name_].set_scalar(scalar3_weight_);
+
     auto* one_hot_feat = weights[one_hot_name_].mutable_one_hot();
     one_hot_feat->set_default_weight(one_hot_default_weight_);
-    (*one_hot_feat->mutable_weights())[one_hot_elem1_name_] = elem1_weight_;
-    (*one_hot_feat->mutable_weights())[one_hot_elem2_name_] = elem2_weight_;
-    (*one_hot_feat->mutable_weights())[one_hot_elem3_name_] = elem3_weight_;
+    (*one_hot_feat->mutable_weights())[one_hot_elem1_name_] =
+        one_hot_elem1_weight_;
+    (*one_hot_feat->mutable_weights())[one_hot_elem2_name_] =
+        one_hot_elem2_weight_;
+    (*one_hot_feat->mutable_weights())[one_hot_elem3_name_] =
+        one_hot_elem3_weight_;
+
+    SparseWeights* sparse_feat = weights[sparse_name_].mutable_sparse();
+    sparse_feat->set_default_weight(sparse_default_weight_);
+    (*sparse_feat->mutable_weights())[sparse_elem1_name_] =
+        sparse_elem1_weight_;
+    (*sparse_feat->mutable_weights())[sparse_elem2_name_] =
+        sparse_elem2_weight_;
+
+    BucketizedWeights* bucketized_feat =
+        weights[bucketized_name_].mutable_bucketized();
+    bucketized_feat->set_default_weight(bucketization_default_weight_);
+    for (const float boundary : bucketization_boundaries_) {
+      bucketized_feat->add_boundaries(boundary);
+    }
+    for (const float weight : bucketization_weights_) {
+      bucketized_feat->add_weights(weight);
+    }
+
     return proto;
   }
 
@@ -31,19 +56,31 @@ class GenericLogisticRegressionInferenceTest : public testing::Test {
   const std::string scalar2_name_ = "scalar_feature2";
   const std::string scalar3_name_ = "scalar_feature3";
   const std::string one_hot_name_ = "one_hot_feature";
-  const std::string one_hot_elem1_name_ = "elem1";
-  const std::string one_hot_elem2_name_ = "elem2";
-  const std::string one_hot_elem3_name_ = "elem3";
+  const std::string one_hot_elem1_name_ = "one_hot_elem1";
+  const std::string one_hot_elem2_name_ = "one_hot_elem2";
+  const std::string one_hot_elem3_name_ = "one_hot_elem3";
   const float bias_ = 1.5f;
   const float threshold_ = 0.6f;
   const float scalar1_weight_ = 0.8f;
   const float scalar2_weight_ = -2.4f;
   const float scalar3_weight_ = 0.01f;
-  const float elem1_weight_ = -1.0f;
-  const float elem2_weight_ = 5.0f;
-  const float elem3_weight_ = -1.5f;
+  const float one_hot_elem1_weight_ = -1.0f;
+  const float one_hot_elem2_weight_ = 5.0f;
+  const float one_hot_elem3_weight_ = -1.5f;
   const float one_hot_default_weight_ = 10.0f;
   const float epsilon_ = 0.001f;
+
+  const std::string sparse_name_ = "sparse_feature";
+  const std::string sparse_elem1_name_ = "sparse_elem1";
+  const std::string sparse_elem2_name_ = "sparse_elem2";
+  const float sparse_elem1_weight_ = -2.2f;
+  const float sparse_elem2_weight_ = 3.1f;
+  const float sparse_default_weight_ = 4.4f;
+
+  const std::string bucketized_name_ = "bucketized_feature";
+  const float bucketization_boundaries_[2] = {0.3f, 0.7f};
+  const float bucketization_weights_[3] = {-1.0f, 1.0f, 3.0f};
+  const float bucketization_default_weight_ = -3.3f;
 };
 
 TEST_F(GenericLogisticRegressionInferenceTest, BaseTest) {
@@ -59,7 +96,7 @@ TEST_F(GenericLogisticRegressionInferenceTest, BaseTest) {
   float score = predictor.PredictScore(example);
   float expected_score =
       Sigmoid(bias_ + 1.0f * scalar1_weight_ + 42.0f * scalar2_weight_ +
-              0.666f * scalar3_weight_ + elem1_weight_);
+              0.666f * scalar3_weight_ + one_hot_elem1_weight_);
   EXPECT_NEAR(expected_score, score, epsilon_);
   EXPECT_EQ(expected_score >= threshold_, predictor.Predict(example));
 }
@@ -99,7 +136,7 @@ TEST_F(GenericLogisticRegressionInferenceTest, UnknownFeatures) {
   auto predictor = GenericLogisticRegressionInference(GetProto());
   float score = predictor.PredictScore(example);
   // Unknown features will be ignored.
-  float expected_score = Sigmoid(bias_ + elem2_weight_);
+  float expected_score = Sigmoid(bias_ + one_hot_elem2_weight_);
   EXPECT_NEAR(expected_score, score, epsilon_);
 }
 
@@ -177,4 +214,77 @@ TEST_F(GenericLogisticRegressionInferenceTest, NoThreshold) {
   EXPECT_FALSE(predictor.Predict(example));
 }
 
+TEST_F(GenericLogisticRegressionInferenceTest, PreprossessedModel) {
+  GenericLogisticRegressionModel proto = GetProto();
+  proto.set_is_preprocessed_model(true);
+  // Clear the weights to make sure the inference is done by fullname_weights.
+  proto.clear_weights();
+
+  // Build fullname weights.
+  Map<std::string, float>& weights = *proto.mutable_fullname_weights();
+  weights[scalar1_name_] = scalar1_weight_;
+  weights[scalar2_name_] = scalar2_weight_;
+  weights[scalar3_name_] = scalar3_weight_;
+  weights[ExamplePreprocessor::FeatureFullname(
+      one_hot_name_, one_hot_elem1_name_)] = one_hot_elem1_weight_;
+  weights[ExamplePreprocessor::FeatureFullname(
+      one_hot_name_, one_hot_elem2_name_)] = one_hot_elem2_weight_;
+  weights[ExamplePreprocessor::FeatureFullname(
+      one_hot_name_, one_hot_elem3_name_)] = one_hot_elem3_weight_;
+  weights[ExamplePreprocessor::FeatureFullname(
+      sparse_name_, sparse_elem1_name_)] = sparse_elem1_weight_;
+  weights[ExamplePreprocessor::FeatureFullname(
+      sparse_name_, sparse_elem2_name_)] = sparse_elem2_weight_;
+  weights[ExamplePreprocessor::FeatureFullname(bucketized_name_, "0")] =
+      bucketization_weights_[0];
+  weights[ExamplePreprocessor::FeatureFullname(bucketized_name_, "1")] =
+      bucketization_weights_[1];
+  weights[ExamplePreprocessor::FeatureFullname(bucketized_name_, "2")] =
+      bucketization_weights_[2];
+  weights[ExamplePreprocessor::FeatureFullname(
+      ExamplePreprocessor::kMissingFeatureDefaultName, one_hot_name_)] =
+      one_hot_default_weight_;
+  weights[ExamplePreprocessor::FeatureFullname(
+      ExamplePreprocessor::kMissingFeatureDefaultName, sparse_name_)] =
+      sparse_default_weight_;
+  weights[ExamplePreprocessor::FeatureFullname(
+      ExamplePreprocessor::kMissingFeatureDefaultName, bucketized_name_)] =
+      bucketization_default_weight_;
+
+  // Build preprocessor_config.
+  ExamplePreprocessorConfig& config = *proto.mutable_preprocessor_config();
+  config.add_missing_features(one_hot_name_);
+  config.add_missing_features(sparse_name_);
+  config.add_missing_features(bucketized_name_);
+  (*config.mutable_bucketizers())[bucketized_name_].add_boundaries(
+      bucketization_boundaries_[0]);
+  (*config.mutable_bucketizers())[bucketized_name_].add_boundaries(
+      bucketization_boundaries_[1]);
+
+  auto predictor = GenericLogisticRegressionInference(proto);
+
+  // Build example.
+  RankerExample example;
+  Map<std::string, Feature>& features = *example.mutable_features();
+  features[scalar1_name_].set_bool_value(true);
+  features[scalar2_name_].set_int32_value(42);
+  features[scalar3_name_].set_float_value(0.666f);
+  features[one_hot_name_].set_string_value(one_hot_elem1_name_);
+  features[sparse_name_].mutable_string_list()->add_string_value(
+      sparse_elem1_name_);
+  features[sparse_name_].mutable_string_list()->add_string_value(
+      sparse_elem2_name_);
+  features[bucketized_name_].set_float_value(0.98f);
+
+  // Inference.
+  float score = predictor.PredictScore(example);
+  float expected_score = Sigmoid(
+      bias_ + 1.0f * scalar1_weight_ + 42.0f * scalar2_weight_ +
+      0.666f * scalar3_weight_ + one_hot_elem1_weight_ + sparse_elem1_weight_ +
+      sparse_elem2_weight_ + bucketization_weights_[2]);
+
+  EXPECT_NEAR(expected_score, score, epsilon_);
+  EXPECT_EQ(expected_score >= threshold_, predictor.Predict(example));
+}
+
 }  // namespace assist_ranker

components/assist_ranker/proto/generic_logistic_regression_model.proto

@@ -8,6 +8,8 @@ syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
+import "example_preprocessor.proto";
+
 package assist_ranker;
 
 message SparseWeights {
@@ -69,4 +71,15 @@ message GenericLogisticRegressionModel {
   // Map of weights keyed by feature name. Features can be scalar, one-hot,
   // sparse or bucketized.
   map<string, FeatureWeight> weights = 3;
+
+  // If it's a preprocessed_model, then use preprocessor_config to preprocess
+  // the input and fullname_weights to calculate the score.
+  optional bool is_preprocessed_model = 4;
+
+  // Map from feature fullname to it's weights.
+  map<string, float> fullname_weights = 5;
+
+  // Config for preprocessor (without feature_indices; there is no need for
+  // vectorization, since the inference model use ExampleFloatIterator instead).
+  optional ExamplePreprocessorConfig preprocessor_config = 6;
 }