content: /*
   * Tencent is pleased to support the open source community by making Angel available.
   *
   * Copyright (C) 2017-2018 THL A29 Limited, a Tencent company. All rights reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * https://opensource.org/licenses/Apache-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License
   * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
   * or implied. See the License for the specific language governing permissions and limitations under
   * the License.
   *
   */
  package com.tencent.angel.sona.tree.gbdt.tree;
  
  import com.tencent.angel.sona.tree.basic.split.SplitEntry;
  import com.tencent.angel.sona.tree.gbdt.histogram.GradPair;
  
  import java.io.Serializable;
  
  public class GBTSplit implements Serializable {
      private SplitEntry splitEntry;
      private GradPair leftGradPair;  // grad pair of left child
      private GradPair rightGradPair; // grad pair of right child
  
      public GBTSplit() {
          this(null, null, null);
      }
  
      public GBTSplit(SplitEntry splitEntry, GradPair leftGradPair, GradPair rightGradPair) {
          super();
          this.splitEntry = splitEntry;
          this.leftGradPair = leftGradPair;
          this.rightGradPair = rightGradPair;
      }
  
      public boolean isValid(float minSplitGain) {
          return splitEntry != null && !splitEntry.isEmpty()
                  && splitEntry.getGain() > minSplitGain;
      }
  
      public boolean needReplace(GBTSplit split) {
          if (this.splitEntry != null)
              return split.splitEntry != null && this.splitEntry.needReplace(split.splitEntry);
          else
              return split.splitEntry != null;
      }
  
      public void update(GBTSplit split) {
          if (this.needReplace(split)) {
              this.splitEntry = split.splitEntry;
              this.leftGradPair = split.leftGradPair;
              this.rightGradPair = split.rightGradPair;
          }
      }
  
      public SplitEntry getSplitEntry() {
          return splitEntry;
      }
  
      public void setSplitEntry(SplitEntry splitEntry) {
          this.splitEntry = splitEntry;
      }
  
      public GradPair getLeftGradPair() {
          return leftGradPair;
      }
  
      public GradPair getRightGradPair() {
          return rightGradPair;
      }
  
      @Override
      public String toString() {
          return String.format("split: %s, left grad pair: %s, right grad pair: %s",
                  splitEntry, leftGradPair, rightGradPair);
      }
  
  }
  